Annie's half-sister Lily shows up on her doorstep to discuss an important family matter after Annie refused to contact her. Eric tries to figure out why Annie won't contact Lily. Meanwhile, Cecilia sets Martin's friend Mac up with a girl from school, but he doesn't want to go out with her because of something embarrassing that happened ten years ago; Ruthie and Peter put a bad spin on a school project that lands them in trouble when they create a newspaper featuring false and derogatory stories about two former US presidents. Lastly, Roxanne turns to Chandler when she finds herself faced with a moral dilemma as she is keeping a secret from Kevin regarding Detective Michaels.

It's Camden chaos all around when Matt, who is having problems in his marriage to Sarah, returns to Glenoak for a visit and runs into his ex-girlfriend Heather on his flight to Glenoak. Simon unexpectedly announces he's coming home for the summer.

Also, Lucy sets out to discover why Roxanne is suddenly too busy to hang out with her as she's convinced that Roxanne is secretly trying to become a detective behind Kevin's back. Ruthie keeps a secret about a fellow student from her parents. Lastly, Martin learns that his baseball teammates think he's having sex with Cecilia.

The Camden chaos continues with Matt, who is trying to salvage his marriage, questioning whether he still has feelings for his ex-girlfriend Heather; Simon's return to Glenoak creates conflicted feelings for his ex-girlfriend Cecilia, who is torn between her feelings for Simon and her current boyfriend Martin; Ruthie's foreign exchange student friend Maria, appears to be making the moves on Ruthie's boyfriend Peter; and grandparents-to-be Eric and Annie hop a plane for New York, despite Mary's repeated pleas for her family to stay away.