Lorenzo, an Italian journalist, is believed to have information concerning who in America is funding activities of the Mafia in Italy. He will not reveal the names until he has returned to Rome and written his story. Steve Mitchell is assigned to protect him on his flight to Paris and then on the train to Rome. However, Mitchell has not been informed that Lorenzo has agreed to protection from the Italian police, and Mitchell ends up watching the wrong man. When Lorenzo is murdered on the flight, Mitchell must work together with Gramati, an Italian police inspector, to identify the killer.