Halloween night finds the ER awash with allergic or otherwise incapacitated children. Kerry tolerates a visiting candidate for chief while she waits for the official vote. Romano operates on an 11-year-old girl and finds she's genetically male. Carter leaves Lucy in charge of a dorm party he's supposed to be overseeing, with unfortunate results. Mark learns that Jenn's moving to St. Louis--with Rachel. Mark and Carol treat a pregnant schizophrenic.
Elenco: Maura Tierney , Parminder Nagra , Scott Grimes , Linda Cardellini , John Stamos , David Lyons , Angela Bassett , Laura Innes , Lily Mariye , Linda Cardellini , Maura Tierney , Mekhi Phifer , Noah Wyle , Parminder Nagra , Scott Grimes , Sherry Stringfield , Yvette Freeman , Eriq La Salle , Kellie Martin , John Stamos , Michael Michele , Erik Palladino , Angela Bassett , David Lyons , Chase Masterson , Swoosie Kurtz , Lisa Vidal , Laura Cerón .