When Jess (Zooey Deschanel) runs into her ex-boyfriend, Paul (guest star Justin Long), and Nick (Jake Johnson) runs into his ex-girlfriend, Caroline (guest star Mary Elizabeth Ellis), the gang fears they may "backslide" into relationships with them. Meanwhile, Schmidt (Max Greenfield) desperately tries not to get aroused as he deals with a delicate medical issue, and Winston (Lamorne Morris) suffers the consequences of a wild night out.