This is a satisfying intrigue/murder/noir that by rights should be out on DVD in a restored print. Peter Lorre gets fourth billing, after Sydney Greenstreet, Fay Emerson and Zachary Scott, but he's the star of the show.
The movie is set between the wars and Lorre plays a mystery writer visiting Ankara who, at a party, meets a Turkish police officer who loves mysteries. The officer tells Lorre the story behind a body washed up the day before with a stab wound in its side and papers identifying it as a vicious crook named Dimitrios. Lorre becomes interested and decides to find out more about the fellow. In a series of flashbacks we learn just how bad a guy Dimitrios was: a killer, blackmailer, political assassin, dealer in stolen government secrets, a man who betrayed every man and woman he came into contact with. Lorre visits several people who are willing to talk about Dimitrios, but only when they learn he's dead. He works his way from Istanbul to Paris, and on the journey meets Sydney Greenstreet, another man with secrets who is interested in Dimitrios. It just might be that it wasn't Dimitrios' body that was found, and if that's true then it could get very dangerous for Lorre. As Emerson's character says, "I've known many men, but I've been afraid of only one...Dimitrios."
The movie has a great noir look about it, with lots of shadows, smoky rooms and harsh facial lighting. The movie features a number of Warner's contract character actors whose names you don't recall but whose faces are memorable, Eduardo Ciannelli, Steven Geray, John Abbott, Victor Francen, George Metaxa (a guy I last saw as Fred Astaire's competition for Ginger Rogers in Swingtime).
And best of all, of course, is the pairing of Lorre and Greenstreet. Lorre is great as a naive, sincere writer who can rise to protect a friend. And Greenstreet can be menacing and sympathetic at the same time.
If you like international intrigue with a noir look and a good story, this is worth getting, although I hope it comes out on DVD. You might also like the book by Eric Ambler, A Coffin for Dimitrios.