After discovering she's inherited a remote island in Canada from the estranged grandfather she was never allowed to meet, 17-year-old Annie Jacobson decides to investigate, pulling her into a world of buried secrets, unexpected sisterhood, and the complicated family history she was never meant to find.

The Runaways frantically search for their captured friends Chase Stein, Gert Yorkes, and Karolina Dean. The kids go head to head with an unstoppable enemy who has targeted Leslie — or more accurately, the child she's carrying. Nico Minoru draws them all into a dark realm where its ruler Morgan le Fay is much more nefarious than anyone the kids have yet to face.

The Runaways have left their homes (and evil parents) behind and now have to learn to live on their own. As they scavenge for food, search for shelter, and take care of one another, our kids begin to realize that, for better or worse, they’re stuck with each other. And it’s up to them to take down PRIDE once and for all. But someone sent a mysterious message to Jonah… Is there a mole in the Runaways? Meanwhile PRIDE is focused on finding their children, and Jonah has his own dangerous plan in mind.

Every teenager thinks their parents are evil. But what if they really were? When six L.A. teens stumble onto a terrible secret, they realize their parents have been lying to them all their lives. But what are their parents after? And why? While the kids investigate, the adults start to wonder if their kids are hiding secrets of their own. The parents close in on the truth just as the kids uncover a plan with devastating consequences. Now, this unlikely crew of teenagers must band together to stop their parents before it's too late.

Serena has gone off the grid, beyond even the reach of Gossip Girl. Her friends fear for the worst and hope for the best, but even they can't imagine where they will ultimately find her. Meanwhile, Blair has offered Chuck her heart, but is her love enough to help him win back his empire? Lonely Boy Dan has written a new book that promises to make even more trouble than the first, and this time he has no desire to remain anonymous. Nate is determined to finally reveal the true identity of Gossip Girl, thereby making a name for The Spectator, and himself. Lily and Rufus turn on one another when Rufus makes a surprising new ally who threatens Lily and her family. Anywhere else it would be too much drama to handle, but this is the Upper East Side.

The season began in Los Angeles when a re-energized Chuck and Nate decided to pay Serena a visit. Chuck has a newfound philosophy and says "yes" to everything, even death defying stunts. Serena continues to work on the movie set, and is offered a full-time job at the end of the episode. Nate begins an affair with an older woman, Diana Payne, who may have an ulterior motive for being with Nate. Back in New York, Dan learns that Vanessa has published one chapter of his novel, and Blair continues to plan her wedding to Louis, and she also learns she is pregnant. After realizing she still had feelings for Chuck, Blair and Chuck decide to go away together, but their car crashes. As a result of the crash Blair loses her baby, Chuck nearly dies, and Blair eventually marries Louis. The season also focuses on Nate running an online gossip site NYSpectator, Blair and Dan's friendship turning into a relationship, Chuck's quest to find his real parents which leads him to discover that his father, Bart, is still alive, and the effects of CeCe's death on Lily and her marriage to Rufus. At the end of the season, Blair makes a choice between Dan and Chuck, and Lily makes a choice between Rufus and Bart. Serena is seen leaving town while Dan decides to write a new book about the Upper East Side, with the help of Georgina.

Season four's main mystery revolves around Juliet Sharp, a secretive girl with an agenda against Serena involving her past. The second half of the season builds on the complications of Serena's new found relationship with her former teacher Colin, Chuck trying to regain control of Bass Industries from Russell Thorpe, and Dan and Blair's growing friendship. The season also focuses on Lily's past betrayals coming back to haunt her; Chuck and Blair's tumultuous relationship after their break up; Dan and Vanessa's deteriorating friendship; and the arrival of Serena's cousin Charlie Rhodes to the Upper East Side. By the end of the season, Blair has ignored Chuck, Dan has told Vanessa they are no longer friends, and Serena is on that single grind.

Welcome back, Upper East Siders. Summer is officially drawing to a close. Rufus, Dan and Jenny spent the summer in the Hamptons, adjusting to the van der Woodsen's glamorous lifestyle surprisingly faster than any of them expected. Blair and Chuck are madly in love and adjusting to their new "in a relationship" status. Nate returns from his travels with a mysterious brunette in tow. Serena returns from her European adventure with many secrets to hide as she gets ready to move into her dorm at Brown. Blair is determined to have her Queen status at NYU, along with Dan and Vanessa, but her roommate sets out to ensure that she does not retain her title.

Sex, lies and scandals never take a vacation. Rumors is the temperature began to climb between Nate and Serena, who escaped to Hamptons for the summer following their break-up with Lonely Boy. As summer draws to a close, Blair returns from abroad with a hot guy on her arm and Dan, who has spent the summer assisting a famous author, decides to head to the Hamptons. Then, everyone gets back to the city for senior year. Applying for college is only one small part of the story as new romances (and some not-so-new romances) bloom and fade, scandals erupt at every turn, and alliances shift even faster than Gossip Girl can send an update.