Casey feels less than welcome at Clayton. Sam asks Paige to spell out the rules of their "casual relationship," while Doug sets boundaries with Elsa.

A peer group meeting leads Sam to an important decision. Detention with Izzie shows Casey they have more in common than she thought.

In peer group, Sam realizes he needs to manage his own money. Doug gets advice from Megan on dealing with Elsa. Evan meets Casey's new friends.

To prepare for college life, Sam sleeps over at Zahid's. Sam's $700 loss reunites Doug and Elsa with Arlo's parents, former friends of theirs.

Casey tells Izzie what Nate did. Sam tries to figure out which colleges to apply to. Doug discovers a need to educate first responders about autism.

Ignoring Casey's wishes, Elsa throws her a big birthday party, while Sam insists on following a decade-old birthday ritual. The bartender haunts Doug.

Cruel yearbook comments show Sam who's got his back, a favor he repays at graduation. Feelings for Izzie confuse Casey. Elsa asks Doug a key question.

Paige invites Sam to redefine their romance, Casey struggles with complicated feelings, and Elsa attempts to find a new normal with Doug.

Sam makes a bold move amid the buzz of orientation day. Casey crosses paths with Nate. Elsa and Doug unpack the hazards of half-truths.

An ethics professor pushes Sam to his limits. Elsa keeps an eye on Doug ... and Megan. Casey considers her future and encourages Evan to do the same.

Casey and Evan take to the open road for a tense reunion. Back home, Sam and Zahid get ready to party, and Elsa bids farewell to the past.

As Paige makes a plan in the face of adversity, Sam awaits a crucial academic update. Elsa endures an uncomfortable encounter.

Sam’s art assignment inspires an impromptu field trip. Casey navigates a fight with Izzie. Evan works hard for a second chance with Doug.

While Sam and Casey face friendship dilemmas, Elsa uncovers a charming surprise, and Doug makes an unexpected decision.

A hard truth keeps Casey up at night. Sam experiences a rough season with Zahid -- and Paige. Elsa and Doug brace for their next chapter.

As Sam gets political with his art, Elsa and Doug explore a (not-so-normal) weekend away. Casey and Izzie re-examine their relationship.

A rogue plan for Zahid leads to a last-minute mission for Sam, Casey, Paige and Abby. Meanwhile, Doug faces a major test and makes a pivotal choice.

Sam's living situation with Zahid gets off to a rocky start, while Elsa struggles with her son's departure. Casey weighs telling Doug about Izzie.

Casey's demanding schedule starts affecting her grades, while Sam seeks out some extra credit himself. A chance run-in revives old suspicions for Elsa.

A change at work leaves Sam scrambling for cash. When Izzie fights the school dress code, Casey feels conflicted. Paige discovers a knack for management.

Casey and Izzie face fallout from the protest. Paige tries to prove her mettle to Casey through strange tasks. Doug avoids dealing with a painful loss.

As Sam gets ready for an adventure, Elsa thinks about ways to discourage him. Casey gets an up-close look at Izzie's tense home life.

Sam seeks a worthy caretaker for Edison. Casey tries to be supportive of Izzie, but her plan backfires. Zahid shares tough news with Sam.

Elsa makes a meaningful reconnection. Paige plans a romantic night with Sam. Pressure mounts on Casey ahead of a big track meet.

As Casey reaches a crossroads, she finds herself questioning a lot of things. But in the meantime, she helps Sam get over a hurdle of his own.

Casey and Sam fume about their parents meddling in their lives. Zahid hosts a big send-off for something near and dear.

Sam deals with a big disappointment, Casey clashes with Elsa over college plans, and a recurring dream vexes Doug.