It should have been a wonderful holiday for the four young people traveling to Venice. Everyone’s so friendly – particularly the charming elderly gentleman who shares his first-class railway carriage with them for part of the way. So it was a shock to find, on arriving in Turin, that their elderly travelling companion has been the victim of robbery with violence. They continue on their way with dampened spirits, only to find that trouble is following them. They have inadvertently walked off with the crucial evidence of a more serious crime – and someone desperately wants to retrieve it.