West and Gordon are ambushed by a Mexican gang called the Pistoleros, who attempt to kidnap the latter. Gordon sets off for Tohachi, Arizona to investigate a picture of himself found on one of the bandits; West continues to their original destination, Fort Challenge. There Charlie Tobin, an old friend, tells West that an impostor has taken the place of Lt. Murray, one of the fort's most important officers. West's attempts to investigate are hindered and Tobin soon ends up dead. Gordon, meanwhile, is drugged and abducted by a mysterious older man. West eventually makes his way to Tohachi to try and locate his partner, who knew Murray and can verify his identity. Things appear to be resolved when Gordon turns up and says that Murray is the real thing. However, only a few minutes afterwards, some Pistoleros appear and gun Gordon down. West now has to expose a conspiracy, prevent a war... and, of course, get revenge.

!!Tropes present in this episode:
* AlmostDeadGuy: Jim gets some important information out of the dying Sanchos, but asks for the name of the head Pistolero just [[HisNameIs a few seconds too late]].
* {{Bandito}}: Ostensibly, the Pistoleros, complete with sombreros and mustaches and such.
* ConvenientlyTimedAttackFromBehind: [[spoiler:Jim storms into the villain's hideout and manages to defeat everyone except the villain, who scrambles out of reach before taking careful aim at Jim with a rifle. At which point Artie arrives behind the villain, calls out to get his attention away from Jim and then shoots the guy dead. It's extra dramatic in that it serves as a revelation 1) to the audience that Artie and co. have escaped, and 2) to Jim that Artie is alive.]]
* DeathFakedForYou: [[spoiler:The villain of the week sends in a fake Artie to verify "Murray"'s identity and then kills the fake Artie in order to further sour diplomatic relations. Fortunately he keeps the real Artie alive for... [[BondVillainStupidity reasons]].]]
* KarmicDeath: Sanchos is apparently [[KnifeNut very proud]] of his custom-made knives; they're basically his trademark. He ends up accidentally running himself through with one of them while fighting Jim.
* PreAsskickingOneLiner: Jim to Sanchos: "Take a good look at the man who's going to kill you." Might have been a PreMortemOneLiner if Sanchos hadn't fallen victim to a KarmicDeath.
* RevengeBeforeReason: Col. Roper tells Jim that operating in Mexico without Col. Vega's sanction will worsen an already shaky border situation. Nevertheless, Jim begins his investigation without informing Vega and, once he finally does ask, Vega realizes that Jim is going to track down Sanchos with or without permission.
* SpotTheImposter: An important plot point in the first part of the episode is trying to figure out whether Murray is an impostor or not. Also, before Tobin will confide in Jim he tests the agent to make sure it really ''is'' Jim.
* StunnedSilence: The horrified version for Jim when Artie is killed [[spoiler:followed later by the amazed version when Artie turns up alive.]]
* SurgicalImpersonation: [[spoiler:This is the method used to create substitutes for Murray, Artie and Roper.]]