In Pilot, After the horrific death of her mother, Cassie travels to the picturesque town of Chance Harbor to live with her warm and loving grandmother Jane Blake. As Cassie begins her first day at her new high school, she comes to know the gentle and kind Diana Meade who invites Cassie to join her and her friends at the Boathouse Bar and Grill. Later, while awaiting for Diana at the Boathouse, Cassie is introduced to Faye Chamberlain and her best friend Melissa Glaser Becoming annoyed by Faye, and impatient with Diana, Cassie decides to leave until her car inexplicably catches fire. After being rescued by the good-looking Adam Conant, Cassie instantly becomes attracted to the young-man. However after the discovery of Adam's relationship with Diana, Cassie backs off.
The following day, Cassie runs into Diana, who tries to apologize for the other day. However, as Cassie struggles to adjust in her new hometown, Diana persuades Cassie to accompanying her to an old abandoned house. Once there, Adam, Diana, Faye, Melissa, and Nick all convince Cassie that they are descended from a long and powerful line of witches, and they've been waiting for her to join them and complete a new generation of the Secret Circle. Refusing to believe them, Cassie runs away, until later when Adam shows her how to harness her magical powers.After witnessing the efficiency of their power, Adam and Cassie fall into a trance where they nearly kiss. Once Cassie realizes what was happening, she pulls away from Adam and runs off again. Later that night, Cassie pays a visit to Adam's father, Ethan Conant, who explains that she and Adam are destined to be together After leaving the Boathouse, Cassie meets up with Diana who tries to explain the history of their magic, and the importance of staying together. Meanwhile, down by the pier, Faye conjures a storm that nearly destroys the entire town. Despite her effort to counteract the spell, Cassie is the only witch strong enough to reverse the damage and to stop the storm.
Later that night, after Cassie returns home she discovers a hidden passage in the wall of Amelia's childhood bedroom. There she discovers an old leather-bound book of spells with message from her mother that explains Cassie's dangerous destiny and the darkness of her past.
In Bound, The following morning, in an effort to distance herself from the Circle and establish a normal teenage life in Chance Harbor, Cassie befriends Sally Matthews, a non-witch. Concerned their powers are getting out of control, Diana pushes everyone to bind the Circle, but Faye is thrilled with the increase in her powers and refuses to participate, while Melissa flirts with Nick despite Faye's warnings. Meanwhile, Adam fights his growing feelings for Cassie, but circumstances continue to throw them together, forcing Cassie to make a decision. {C}Later, the annual Chance Harbor Celebration Festival, Sally is fatally harmed when Faye Chamberlain accidentally pushed her over a balcony. However after Dawn Chamberlain uses a crystal to magically heal Sally, who had little to no memory of what happened After realizing the dangers of their magic, the Circle finally comes to terms with binding their powers.
In Loner, The next day, a cute jock named Luke asks Cassie to the school dance, and after watching Adam spend time with Diana at the Boathouse, she accepts his offer. Meanwhile, Melissa sees the dance as an opportunity to get closer to Nick Faye, on the other hand, has no plans to go and remains focused on finding a way to control her powers. After Dawn discovers an intense man named Zachary Larson, had recently returned to Chance Harbor, she asks Charles to keep an eye on him after he begins asking questions about Cassie and the Circle.
However, after Charles confronts Zach about his intentions, Zachary attacks Charles and later sets off to kill Cassie and her friends. At the dance, Cassie is chased and attacked by Zachary, and the Circle use magic to defeat him.
In Heather, After the "disappearance" of Zachary Larson, Cassie looks up an old friend of her mother's named Heather Barnes and discovers she has been in a catatonic state since the night of the fire sixteen years ago. Feeling guilty that her mother and her Circle may have had something to do with Heather's current state, Cassie tells Diana that she wants to use magic to help Heather. However, after Diana refuses to help, Cassie reluctantly turns to Faye, who is more than happy to conjure up a spell – for a price After Cassie and Faye unknowingly release a demon from its prison, as Faye skims through Cassie's Book of Shadows, the girls are later attacked by Abaddon, who wishes to kill the Circle and steal their powers. However, after the untimely death of Heather Barnes, the demon exits her body and later enters within Melissa.
In Slither, The following day, torn between her loyalties to the Circle and her family, Cassie wrestles with the secrets she must keep from her grandmother. Nick is thrown for a loop when Melissa adopts a new attitude and enlists his help to track down her family's Book of Shadows. Faye is also recruited but isn't happy about being the third wheel. Meanwhile, Diana is craving some alone time with Adam and arranges a date night so they can rekindle the spark in their relationship, but all six of them are brought together to fight off a dark force that threatens to destroy the Circle from within. Completely unaware of the new danger encroaching on their children, Dawn joins Charles aboard his boat to further their plans for the Circle, but is surprised to find that Charles may have more than business on his mind. After countless battles between the Circle and "Melissa", Cassie finally turns to her grandmother for help however after the demon takes Nick to be his next host, the demon is later killed by Charles Meade.
In Wake, Following the death of Nick, when his older brother Jake returns to Chance Harbor, he learns a lot has changed since his last visit. For one, the girl he left behind, Faye, has discovered she's a witch and has plans to get even with the handsome guy who broke her heart. To complicate things further, he sets his sights on the alluring Cassie, much to Adam and Faye's dismay. However Cassie is attacked by a witch hunter named Simone, the Circle must come together to fight off yet another enemy who threatens the coven.
In Masked, Deciding the Circle needs to have a little fun, Faye convinces Cassie to throw a Halloween party. Intent on wooing Jake back, Faye goes all out on her Halloween costume. After a fight with Diana, Adam turns to Cassie for advice. Meanwhile, some dangerous, uninvited guests set their sights on the Circle. With the help of Jake, a group of witch hunters are successfully able to kidnap Cassie and her friends. However the hunters find killing the witches easier said than done, especially with Cassie’s powers growing stronger by the day.
In Beneath, One week has passed since the Circle's encounter with the witch hunters, and with Melissa away visiting relatives the Circle isn't as strong. Meanwhile, after not hearing from her grandmother for a couple of days, Cassie becomes concerned and wants to go look for her. Diana decides the entire Circle should go in case Jane is in trouble. She also invites Jake along, much to Adam's dismay. A storm turns the day trip into an overnight excursion, so Faye suggests a little game of Truth or Dare to liven up the evening. However, things take a horrible turn when Faye is forced to reckon with someone from her past.
As Cassie helps Faye deal with demons of her past, she makes a horrifying discovery when she magically unearths the murdered body of Henry Chamberlain, Faye’s beloved grandfather.
In Balcoin, As Cassie becomes more and more curious of ancestry, she and Jake begin to look into her father's side of the family, hoping to discover more about her lineage and why she has powers separate from the Circle. Meanwhile, Adam becomes protective of Cassie when Faye reveals that Jake might be hiding something dangerous from them. At the same time, Adam's equally concerned when Melissa's cousin Holden comes to town and catches Diana's eye. A power shift forms between Charles and Dawn that threatens to destroy their plan. Later, the Circle is attacked by yet another attempt from the witch hunters to kill the Circle. However, after the discovery of Jake's affiliation with the hunters, the Circle begins to doubt the trust of their friendship.
In Darkness, Cassie turns to Adam when she uncovers a secret about herself that she needs kept from the rest of the Circle, including Diana. Meanwhile, Diana is thrilled when her grandmother Kate drops in for a visit, but Charles is suspicious of his mother's motives after Kate takes an unusual interest in Cassie. Meanwhile, Faye recruits a mysterious stranger named Lee to help her with a spell that could change the balance of the Circle forever.
In Fire/Ice, After Cassie asks Adam for help when she wants to look into her father's past, and their search leads them to an eerily familiar place. It also rekindles an old flame when Adam, thrilled to be spending time with Cassie again, asks her to the Fire and Ice dance. But because of her friendship with Diana, Cassie is forced to give a surprising response. In an effort to be a better father, Ethan offers to chaperone the dance, much to Adam's dismay. Faye asks Lee to help her with a spell that would grant her individual magic. Unfortunately, the spell has some terrifying side effects that nearly destroy the Circle.
In Witness,
After Jake returns to Chance Harbor to warn Cassie that unless they find out how her father was killed in the boat fire sixteen years ago, she'll meet with the same tragic death. However, after Jake suggests an extremely dangerous method to finally uncover what happened on that fateful day, Adam and Diana suspect he may have an ulterior motive. In an effort to usurp the other, both Charles and Dawn try to get Ethan on board as an ally. Faye gets trapped in a dangerous situation when one of Lee's friends, Callum stops by the shop.
In Medallion, After receiving a frightening warning about the witch hunters' return, Cassie enlists the Circle's help. At the same time, her true feelings for Adam and Jake surface during a birthday party that Ethan decides to throw with the help of Diana. Meanwhile, Faye and Melissa take their inner power to a chilling new level when they try a little of Lee's "Devil's Spirit".
In Valentine, In honor of the holiday, Faye and Melissa throw a girls only anti-Valentine's Day slumber party for themselves and
fellow witches Diana and Cassie. But the night gets wilder than expected when Melissa offers Diana some mood altering "Devil's Spirit" and the first person Diana loosens up around is Lee, who crashes the party to help Faye achieve her own power. Meanwhile, Cassie is forced to turn to Adam and Jake after she becomes haunted by the spirits of some vengeful witches. In Return,
Cassie is stunned when a notoriously evil figure from her past shows up on her doorstep. However, her surprise quickly turns to suspicion when he asks her to return the medallion she found in the wreckage of the fire that killed their parents. Cassie storms off but is captured by Eben and his band of witch hunters. Jake offers to trade himself for Cassie's freedom and when Adam realizes they're in trouble he calls the Circle. Meanwhile, Faye and Diana are concerned when Melissa starts spending more time with Callum.
In Lucky, Cassie catches Blackwell sneaking around the abandoned house. After confiding in Adam, he tells her he knows Blackwell was looking for a device to drain witches' powers and clearly back to his old ways. Faye shows up at Lee's house to invite him to the school fundraiser, but is taken aback when Eva greets her at the door claiming to be Lee's girlfriend. Meanwhile, Melissa encourages Diana to date a normal guy and points her in the direction of a new, handsome guy in town. Dawn runs into Blackwell at the school but the reunion isn't quite what she expected.
In Curse, Blackwell warns Cassie and Adam that their love may be destiny, but it's also a curse. He suggests they go visit her grandmother, Jane to find out if there is a spell to reverse it. Jane warns Cassie that someone in the Circle will die if the curse is awakened. Meanwhile, Eva starts stalking Faye and Charles makes his next move against Blackwell.
In Sacrifice, Jake gets a surprise visit from an old acquaintance named Samuel, a witch hunter, who has a message for Blackwell about Eben's surprising next move. Cassie intervenes, forces Samuel to reveal his news and is stunned to find out what Eben is trying to resurrect. Meanwhile, Diana is frustrated that keeping the secrets of who they are is building a barrier between her and Grant. Faye and Melissa agree to help out Adam at the Boathouse and in return get him to help them use their magic to enhance their love life.
In Crystal, Cassie finds out that Diana was her half sister because Royce, Jake's grandfather, said that his Crystal was hidden in a mine and he spelled it so that no Witch with Dark Magic can access it. When Cassie and Jake got to the mine to rescue Adam and Melissa, Cassie started choking and couldn't go in, since she had Dark Magic. Later, Diana said that she couldn't help Melissa and Adam out of the mine either because she was choking as well, meaning that she has dark magic and is the other child of Blackwell in the Circle.
In Traitor, Cassie realized that her grandmother (Jane Blake) is dead, so she falls into sadness and anger believing the witch hunters had killed her grandmother. Adam tried to comfort her and she accidently kissed him, resulting her to be very sorry.While Cassie confronted John that she wants to kill the witch hunters now more than ever. At the Abandoned House, Faye and Jake brought some good news that they found a crystal, but its energy was drained out, but was stolen by the traitor later in the episode. This resulted Cassie, Diana,Jake and Faye into going the most creepiest place on earth-as Faye mentioned, but before that Jake wanted to asked about the witch who was working for Eben so he arranged a meeting with Issac so they came there first. Instead of Issac there, it was Ian who told Jake that Eben had killed Isaac because he had let the traitor escaped and informed him that he never met the traitor. Cassie then attacked Ian by sufficating him causing Diana and Jake to try and stop her, after that Ian critisized Jake and went away.When half the circle and Cassie arrived there, the creepiest place on Earth actually was an The Abandoned Carnival.
As the circle went in they were seperated into two groups; Faye with Jake and Cassie with Diana even though Diana wanted to go with Faye instead because she doesn't want to talk with Cassie about her being half-sister of Cassie, but Faye said she doesn't want to go with any of the dark magic super twins with her which changed Diana's mind of going with Faye. Cassie tried to talk with Diana that dark magic isn't that bad, but it can save people like she saved Diana during the time Luke almost killed Diana (Masked). When both Diana and Cassie heard a noise they ran there and saw the traitor.Cassie decided to kill the traitor, but Diana insisted not to so she just knock him down. They discovered the traitor was Nick who they believed to be dead. They then chased him saying they don't want to harm him, but just wanted the crystal which he dropped and ran away.
In Prom, After the group is done discussing the fact that Nick is in fact the traitor. John tells Cassie that the crystal is somewhere in the highschool and that Balcoin blood has a special connection to the crystals. He gives her instructions n how to use her blood to find the crystal. Later that night she goes to the school and tries to use her blood to find the crystal, when she does she gets a vision of her mother walking down the hall holding the crystal before the vision ended. She later shares her vision with Diana asking her for her help so they an see a longer vision. When she and Diana get to the prom they find an empty classroom. Draw the symbol in their blood, at first it doesn't work but then Diana grabs Cassie's wrist and the vision starts. She and Diana are suddenly in 1995, they follow Cassie's mom who holds the crystal. They learned that John infact planned their circle and that the crystal she and the others needed was hidden in the trophy case. After coming to the realisation that she and the rest of the circle had been manipulated by John. Diana blames Cassie for letting him in as she was doing the same her mother did. After they argue and Diana leaves she's soon joined by Melissa and Adam. When she tells them were the crystal is hidden they hear a loud noise and realise that Nick was eavesdropping. Nick gets the crystal before they do and, Cassie and the others start to chase him. Cassie and the others chase nick to a junk yard. When she see's Nick meeting with Eben, Cassie confronts him using Dark Magic and props the crytal out of his hand. Once she takes it in her hands Eben uses telekinesis to throw her over some cars, knocking her out.
In Family, Cassie and the rest of the circle try to find out a way to save Faye from the witch hunters. Cassie convinces Diana to come meet John with her to form the Crystal Skull so they can save Faye. After Cassie and Diana form the crystal skull John knock out both Cassie and Diana after they oppose him. When Cassie wakes up she realises their in the abandoned house, she then quickly wakes up Diana. When they try to quietly leave when John's back is turned their stopped by a magical barrier. Cassie figures out what John's true intentions were and he tells Cassie and Diana that he planned to use the crystal skull to kill witches who didn't have Balcoin blood. When Adam crawls into the house Cassie notices that the spell John has cast is burning all the non-Balcoin withches. When she failed to break the magical barrier by herself she activates Diana's dark magic. When both has broken trough the barrier, they use the crystal skull to kill John. Later that night with the circle now unbound Cassie lights a fire by herself without using dark magic.