At one end amnesia movies are heavily-plotted thrillers the solution to which depends on the hero's lost identity, like Alfred Hitchcock's ludicrous psychoanalytic murder mystery Spellbound (1945), which is the most famous, though I prefer Christopher Nolan's Memento (2001) starring Guy Pearce. At the other end, they're existential movies, with the suspense focused on the question of identity, like Delbert Mann's Mister Buddwing (1966) starring James Garner, which doesn't work not only because it's overwritten but because if there were ever an actor who came across as knowing who he was it was Garner. The Man Without a Past is in the latter camp, but much more sophisticatedly foxy.

The movie takes place at the bottom of society in Helsinki. The people who take M in live in a corrugated metal shed on the waterfront and hope to get a council flat. When the husband offers to take M out to dinner he means to an outdoor Salvation Army soup kitchen. A man has frozen to death in another one of these sheds, so it's available for M. He has to pay extortionate rent to the unofficial lord of the harbor wasteland, an eminently non-threatening tough guy, who claims his dog Hannibal will kill M if he doesn't make good on the rent. (The dog ends up adopting M.) M gets the money by taking a job with the Salvation Army, where he and Sister Irma (Kati Outinen), a prickly, virginal soup kitchen worker, start a flirtation.

Having discovered by chance that he knows how to weld, M goes to a bank because he can't be paid by the shipbuilding firm that hires him if he doesn't have an account. As he's about to fill in the forms, an angry walrus of a man comes in with a shotgun and "withdraws" money from his frozen account. Because of corporate-law complications the robber's company was driven into bankruptcy and he was not allowed to pay his workers for work they'd already done. M comes into the police's purview while they're investigating the robbery, and they don't like the fact that he can't tell them his name. They think he chooses not to because he's an illegal alien from one of the Russian Republics, and so a xenophobic official attempts to trump up charges against him. This suggests a level of (familiar) leftist social critique about Finnish society, but Kaurismäki has the wrong technique as a screenwriter to give it force. The naturalism is all on the surface; the story floats off in other, less obviously organized, directions. M ends up delivering the stolen cash to the workers, and then the police, having posted his photo to discover his identity, tell him who he is, or was, and he goes back to meet the wife he can't remember.