Season 4 begins with Paige, Spinner, Marco, Jimmy, and Hazel entering Grade 11. Spinner buys a car with the money he's earned at The Dot, and Paige receives a summons to testify at the trial of the guy who raped her.
The pressure of the trial combined with confronting Dean sends Paige into a destructive downward spiral. Craig receives a generous 16th birthday present from his late father, which causes a rift between Craig and Joey.
Marco faces unexpected hurdles in the race for Student Council President when his opponent Alex threatens to out him to the entire school at the election assembly. Meanwhile, Liberty and Emma have a confrontation of their own when Liberty starts spending time with Emma's ex, Chris.
Rick returns to Degrassi, professing to be a changed man. Everyone is suspicious Rick might hurt another girl the way he hurt Terri so a plan develops to run Rick out of Degrassi for good. J.T. is frustrated with his relationship with Manny because they have barely even kissed yet. When a mishap leads to Manny seeing J.T. naked, J.T. begins to wonder whether their lack of physical contact is because he can't measure up to Manny's expectations.
Sean and Ellie's relationship reaches the next level when Sean wants her to move into his apartment. Is Ellie ready to leave her turbulent childhood home and live with the love of her life? Meanwhile, Manny takes over the Spirit Squad carwash when Paige falls ill.
Rick makes friends with Emma and Toby when he steps in as a replacement on the school's quiz show. Things take a turn for the worse when Jay, Spinner, and Alex pull a nasty prank on Rick that embarrasses him in front of the entire school. Rick's vindictive side comes out, leading him to develop a horrible plan for revenge.
Humiliated and furious, Rick returns to Degrassi with a handgun in his backpack and prepares to take revenge on the students of Degrassi for laughing at him. Jimmy sympathizes with Rick and promises to back him up whenever other students harass him. Rick accuses Jimmy of being part of the prank and shoots Jimmy in the back when he tries to run away. Rick then moves on to the next person on his hit list: Emma. When the smoke clears and the lockdown ends, one student will end up dying an untimely death in Degrassi's hallway.
In the aftermath of the school shooting, everyone is grieving and making small steps to moving on. Sean refuses counseling because he claims to have everything under control. As the shock wears off, Sean realizes he may not be as well adjusted as he thinks and ventures home to confront his past. J.T. shuns Toby for having been friends with the school shooter.
Despite everything that transpired between them, Craig and Ashley start to develop a friendship. Craig clashes with his band when he suggests Ashley become their new member. Hazel brings Paige along to a yoga class taught by Mr. Oleander, the hot new teaching assistant.
Craig is suffering from mood swings and Ashley seems to be the only one who can help, Ashley's dad is planning to get remarried, elsewhere J.T. and Liberty attempt to work together on the school musical.
Ever since the trauma of the shooting, Emma has been distancing herself from her friends and neglecting her typical interests. Emma discovers a scandalous secret when she goes to the ravine with Jay but instead of turning everyone in, Emma decides to join in on the raunchy ravine activities.
Emma keeps her "friends with benefits" relationship with Jay a secret and vows not to tell anyone what goes on at the ravine. But when Emma receives some devastating news, can she keep it to herself much longer? Meanwhile, Jimmy is fed up with being pitied and enlists the help of Craig and Marco to sneak out of the rehab center for a concert by his favorite band.
Everyone is thrilled when Jimmy finally returns to school. Unfortunately for Spinner, Jimmy's return means revealing the truth about what happened that fateful day and dealing with the repercussions. Spinner deeply wants to redeem himself but how can he fully be forgiven for telling Rick that the prank was Jimmy's idea? Danny disapproves of the relationship between J.T. and Liberty.
Ellie starts playing cards for fun with Craig, Alex, Dylan, and other friends. However, Alex raises the stakes when she encourages the group to play with real money. Ellie joins the high-stakes game but ends up gambling with her future rather than for fun. Paige has a secret affair with Mr. O and begins to wonder whether he has been telling her the whole truth.
Paige and Matt (Mr. Oleander) desperately try to keep their relationship a secret but it seems to be an impossible mission when Mr. Simpson spies them together at the park and Manny spreads rumors about them to Hazel. Emma has a ladies night and all her girlfriends are head over heals for Emma's new neighbor, Chester.
The war between Manny and Paige continues when Paige takes credit for Manny's choreography in the Spirit Squad's last routine of the year. Manny reaches the breaking point and starts plotting appropriate revenge. Catlin interviews Kevin Smith about his new project called "Jay and Silent Bob Go To Canada, Eh?"
Craig is upset Ashley is going away to London for the summer because he fears she will dump him for someone else. He plans to show up in London to surprise her but his romantic gesture terribly backfires. Jay and Silent Bob start shooting their movie and Catlin makes a big mistake after going to a bar with Kevin Smith.