Naïve mining engineer Mike Lambert Glenn Ford takes a temporary job driving a truck. When the brakes fail while descending a steep highway, he steers his way through a small town and is lucky to dent the pickup of Jeff Cunningham Edgar Buchanan. Jeff demands payment for the damage, but his employer refuses, so Mike ends up paying him himself. Later, the police locate Mike in a bar and arrest him for reckless driving and having an expired license. A total stranger, barmaid and local femme fatale Paula Craig Janis Carter pays his $50 fine. When Mike gets drunk, Paula quits her job and finds him a hotel room. She then meets with her conspirator, Steve Price Barry Sullivan, and tells him, “I found him”; a stranger with the same height and build as Steve but who also has no personal connections in the town.
The next day, Mike goes looking for a job. The clerk at the assay office puts him in touch with Jeff, a prospector who has found a rich vein in an old, abandoned silver mine. He offers to cut Mike in for 10%, a generous offer he quickly accepts. However, Mike makes the mistake of telling Paula all about it. When Jeff goes to get financing from Steve, Paula gets him to turn Jeff down. An opportunist, Steve Price [Barry Sullivan] obtained his position through his wife Beth [Karen Morley]'s father. He has embezzled $250,000 from the bank and hidden it in Paula's safety deposit box. The plan involves a fatal, fiery car crash, with Mike's body to be mistaken for Steve's.
Mike wins some money in a craps game and pays Paula back everything she spent on him. He saw her get in the car with Steve, and is very suspicious of a barmaid with so much money. Paula tells him she persuaded Steve to reconsider Jeff's financing and gullible Mike falls for the lie.
Mike, Steve and Paula drive out to see the mine. On the way back, Steve persuades Mike to stop for a drink at his place. However, when Mike goes to wash his hands, he notices a bath robe which oddly has "Paula" embroidered on it. Still not willing to open his eyes and figure out the danger he is in, Mike gets drunk and passes out. Steve drives him to the spot chosen for the accident, but Paula knocks Steve out instead of Mike and sends the car - and Steve - over a cliff. She is able to convince Mike that he accidentally killed Steve in a drunken rage and that she staged the accident to cover for him. She begs him to run away with her. Mike then learns that the authorities know Steve was killed and Jeff has been accused of his murder. After going to see Jeff in jail, Mike suspects Paula, but has no proof. He goes to question Mrs. Woodworth, pretending to be a reporter. She confirms that a Helen Bailey called while Jeff was meeting Steve. Mrs. Woodworth's suspicious husband calls the police, but Mike punches him and gets away.
Mike asks Paula if she knows Helen Bailey but she denies it verbally; however, her shocked look tells him that the name was her alias. She leaves and heads to the bank to get the money. Mike follows her there and confronts her. She begs him to go with her, but he turns her down, and the police, tipped off by him, place her under arrest.
