In the waning days of the Civil War, Richard Gatling, creator of the gatling gun, offers his invention to the Federal Government. But Gatling is kidnapped by two assassins - under the employ of Tarpas. They also steal his new invention and kill three Union government agents. Soon after, the Pinkerton Agency sends out Cpt. Chris Tanner (himself a former secret service agent) to find Gatling and recover the weapon.