American GIs MacDougall (Charlton Heston) and Contini (Harry Guardino) are undercover in Nazi-occupied Rome. When Contini falls in love with a rebel leader's daughter, the family prepares a celebration, but mistakenly serves all but one of the agents' carrier pigeons for the feast. To cover up the error, a family member replaces the flock with German pigeons -- which in turn bring MacDougall and Contini's messages straight back to the Nazis.