The Ace of Spades (1935)

The wife of a candidate for Parliament is having an affair with the brother of her husband's rival. The rival candidate, Trent, is running for election on a promise of building a railway that the community needs, but a wealthy landowner won't give permission for the railway to be built over his land. When the landowner is later found dead, suspicion falls on Trent and only his brother can rescue him, but will he risk exposing his secret love to do it.