The Silent Partner is a Canadian film from 1978 based on a Danish novel, Think of a Number, by Anders Bodelsen. The script was an early work of Curtis Hanson, whose later screenplays included L.A. Confidential. The score was written by Oscar Peterson and the lead roles were taken by Elliot Gould, Susannah York, and Christopher Plummer. In other words, there was a lot of talent at work here, and it shows.
Gould plays Miles Cullen, a bank teller who works alongside Julie Carver (York). Unsurprisingly, he fancies Julie, but she is having a rather desultory affair with the bank manager. When Miles realises that someone dressed up as Santa Claus is planning to rob the bank, he craftily arranges things so that the robber gets away with small change, while he keeps the money supposedly stolen. The snag is that the villain he has cheated (Harry Reikle, played by Plummer) is a violent psychopath, who is determined to take revenge on Miles as well as getting his money back.
Miles contrives Reikle's arrest on another charge, and although his attempt to seduce Julie doesn't end well, he finds comfort in the company of another beautiful and adoring young woman, Elaine (Celine Lomez). But is Elaine all that she seems?
Although Julie's part is under-written, with the result that York, a terrific actor, is given some rather banal dialogue, this is a twisty and entertaining film, with one or two shocking moments of violence. Plummer is excellent - as usual - and Gould, an actor whom I find a bit erratic, is on good form here. I'm surprised this film isn't better known. I enjoyed it, and I'm keen to read the book to see how different (or similar) it is.