When the son of the owner of a shipping line is given a secret letter by his father, he thinks nothing of it as he enjoys the privileges of his wealth on the journey to Shanghai. The thing is, though, someone else is determined to know about the contents of the letter and "Bob" (Thomas Beck) quickly finds himself at the centre of quite a conspiracy. Fortunately, the enigmatic "Moto" (Peter Lorre) also happens to be travelling, incognito of course, on the same boat and he recognises a tattoo on the steward's arm as that of a killer he'd encountered before. Whilst "Moto" is working to find out what's going on, "Bob" has taken quite a shine to the mysterious "Gloria" (Virginia Field) but who exactly is she, and what's her agenda? Boats usually serve well as confined spaces to base a thriller, but as this never sets foot outside the studio in the first place that doesn't - aside from the occasional audio splash - really add much to this rather pedestrian drama that offers a few twists and turns but still largely telegraphs the denouement. Still, Peter Lorre brings an engaging charisma to the proceedings, there's plenty of flying furniture and it did rather make me pine for the glamour days of grand sea travel.