When Bob Carey is released from prison after a long sentence for murder, begins the search for Mary, his former girlfriend. But soon he finds out that during his absence, she has married Clifford, a wealthy landowner. The happiness of that marriage is only apparent, Mary, in fact, is seriously ill, suffering from a brain tumor whose pains she attributes to an imaginary pregnancy. It becomes necessary to bring to the city of Laredo for an operation, so Clifford sells all his possessions and begins the long journey towards hope. Soon others will join the expedition: a former army scout named Rogers, a nice Chinese cook, Lin-Chu, and a mestizo that responds to the name of "Bets".