In 1870 Texas, a gang of gun smugglers supplies arms, ammunition and whiskey to Indians. Undercover government agent Martin Benson helps the army eliminate such smugglers. However, the army still needs to know the identity of the man in charge of the gang and the location of their latest hideout. Martin Benson wants to retire but the army asks him to find the head of the smugglers. The army arguments that Benson is the best agent for the job even if another undercover agent, Tony Guy, has already penetrated the smugglers' outfit. A huge payment in gold coins is also offered to Benson as an enticement. Benson agrees to this last assignment and heads out of the army fort. On the trail, many gun runners and bandits try to ambush him and have him killed. In the nearest town, at the Benson farm, a group of smugglers raid and ransack the farm and kill Martin Benson's parents. They also rape his sister, Jenny. The other Benson siblings, Arias, Susy and Daniel are in town buying supplies. When they return to the farm, they find their parents dead and sister Jenny in shock and unable to speak. They also find a wounded man in the shed. Jenny seems terrified of him and the siblings assume the wounded man is one of the bandits, possibly the one who raped Jenny. Motivated by revenge, the older brother Daniel, wants to kill the wounded bandit but changes his mind when he realizes that he could extract vital information about the gang from the wounded man. Daniel decides to save the life of the wounded outlaw by all means and force him to reveal the identity of the other gang members. When the sheriff's posse arrives at the farm, the Benson children conceal the fact there is a wounded bandit in their shed. One posse member is local businessman Vic Graham who adores Susan Benson but Susan was never interested in him. After the posse leaves the farm, Daniel sends for the town doctor to come and patch-up the wounded outlaw. When Martin Benson finally arrives in town, he is given the sad news about his family's tragedy. Susan and Daniel take Martin to the local caves where they have relocated the wounded bandit. When Martin Benson comes face to face with the wounded outlaw everyone has a shocking surprise.