Emma, a divorced single mother seeking to start her life over, moves to a small town in Arizona. She befriends Murphy, the older local pharmacist, but things turn complicated when her ex-husband shows up.

A renowned former army scout is hired by ranchers to hunt down rustlers but finds himself on trial for the murder of a boy when he carries out his job too well. Tom Horn finds that the simple skills he knows are of no help in dealing with the ambitions of ranchers and corrupt officials as progress marches over him and the old west.