An off beat family of New Yorkers must come to terms with their own misgivings about life, relationships and the sheer unpredictability of love itself. Petunia weaves together the lives of brothers Charlie (Tobias Segal), Adrian and Michael (Eddie Kaye Thomas) as they unlearn everything their psychoanalyst parents have taught them. While Michael's cynical wife Vivian (Thora Birch) discovers she is pregnant, the family is also changing. Charlie's would be boyfriend George (Michael Urie) is in a polyamorous relationship with fitness fanatic Robin (Brittany Snow) and Adrian has developed a unrelenting sex addiction. Meddling parents Felicia (Christine Lahti) and Percy (David Rasche) must decide whether to reignite the spark in their relationship or start all over again. Petunia is a film about a dysfunctional family unit on the verge of a nervous breakdown. This is the story of how they pick up the pieces.

In Europe, a group of American college athletes unknowingly board a train that will become one deadly ride.