When Dana (Analeigh Tipton) replaces Peter (Jake McDorman) with Tucker as her plus one to an old friend's wedding, Peter quickly realizes that he'd rather have a miserable time with Dana than a wonderful time without her. Amy (Jade Catta-Preta) skips her spin class to secretly take dance lessons in preparation for the wedding and David (Nicolas Wright) thinks she might be having an affair.

When Peter (Jake McDorman) learns that Dana (Analeigh Tipton) is still friends with all of her exes, even the one who proposed, he takes her cue and tries to reconnect with his one long-term girlfriend and things go horribly wrong. There is conflict at Cooper & Sons when Amy (Jade Catta-Preta) fills in for the receptionist and tries to tell everyone how to do their job.