Two Americans, Phoebe and Julian, team up to return a lost dog to Monte Carlo, hoping to split a $5,000 reward. However, their plan unravels when they find the dog's owner dead, and they become fugitives, entangled in a web of misfortune and mistaken identities.

Once Upon a Crime...
Two American tourists in Rome discover a dog with a $5,000 reward and decide to return it to its owner in Monte Carlo. However, their mission becomes complicated when they arrive to find the owner brutally murdered, leaving them and three other American passengers on the train as prime suspects.