Patrick Heusinger

As the summer draws to a close in the Hamptons, Serena and Nate have everyone fooled into thinking they are a couple to cover up the fact that Nate has been hooking up with a married, older woman. Blair returns from abroad with a hot guy on her arm making a very jealous Chuck question his decision to leave Blair stranded at the heliport. Dan has spent the summer assisting a famous author. While interning for Eleanor Waldorf's company, Jenny sneaks an invite to a much-coveted Hamptons' White Party at which Eric introduces her to socialite Tinsley Mortimer.

Blair is over the moon to be dating royalty and has every intention of becoming a royal herself, but a scheming Chuck has other plans for Blair and her new love, Marcus (recurring guest star Patrick Heusinger). Serena and Dan agree to keep their recent hookups a secret from their friends and family until they figure out what it means for their relationship. Meanwhile, Nate learns the downside to having an affair with a hot older woman, Catherine (recurring guest star Madchen Amick), who is married.

Serena and Dan are forced to deal with their unspoken problems while trapped in an elevator during a citywide blackout. In a humorous twist, Blair questions the lack of passion in her relationship with Marcus (recurring guest star Patrick Heusinger), while, at the same time, Chuck appears to have lost his "passion" for any woman other than Blair. Meanwhile, Nate struggles between his feelings for Vanessa and his more-complicated-by-the-day relationship with Catherine (recurring guest star Madchen Amick). Plus, Jenny risks losing her internship when Eleanor (recurring guest star Margaret Colin) catches Jenny critiquing one of the Eleanor Waldorf designs.

While in the park, a family stumbles upon the sexually mutilated body of Clyde Vandyne, a member of a biker gang known for prostitution and contract killing. To everyone’s surprise, incriminating DNA evidence points to Detective Benson (Mariska Hargitay) as the prime suspect. Munch (Richard Belzer) and Fin (Ice-T) investigate the murder, while Stabler (Christopher Meloni) fights to prove his partner’s innocence. The detectives must find the missing link to both Vandyne’s murder and Benson’s involvement. Also starring: Dann Florek (Captain Donald Cragen), and Tamara Tunie (Dr. Melinda Warner).

As her husband's legal team continues to mount the case for his appeal, Alicia discovers evidence of possible jury tampering in her firm's class action law suit against a major pharmaceutical company.