Serena's family and friends finally put it together that she's missing, but she turns up quickly; in a hotel room, looking like she'd simply partied herself out. Everyone gathers in the hospital, sure that Serena has done this to herself. Lily starts exploring rehab options, and she agrees to an involuntary hold on S, who's obviously none too pleased to go all Girl, Interrupted.
One person still has Serena's back: Dan. When he goes to check on her, she tells him the last thing she remembers was going into the party to kiss him. It's enough to get Lonely Boy to spring her from her posh cell, but before they can become fugitives, Lily finds them at the loft. Dan talks back to Lily about her mothering skills, but when Gossip Girl blasts a photo of "Serena" overdosing, Serena herself asks to be taken back to the institution. Craziness can't stop the Serena/Dan reunion train; they smooch before S goes back to rehab.