Bob Wilson, who becomes a tramp after being jilted by his fiancee, prevents the Limited Mail from being wrecked during a mountain storm and becomes fast friends with Jim Fowler, a railway mail clerk. Jim gets Bob a job on the railroad, and Bob works himself up to the position of engineer on the Limited. Both of the men fall in love with Caroline Dale, but she prefers Bob. A runaway freight runs into the Limited, and Jim is killed. Bob becomes a tramp again, making pals with an ex-convict. When the sides of a tunnel give way, Bob again prevents a train wreck and is reunited with Caroline, who is a passenger on the train. Jim's son, Bobby, is saved from drowning in a mountain stream by the ex-con, and Bob and Caroline make plans to be married.