Chad and Joe want to go to an annual festival at San Gill. However, Capt. Parmalee is leaving town to give a speech and puts the Rangers in charge of the Laredo office while he's away. Then, when Reese returns from an assignment, Chad and Joe trick Reese into assuming the role of "acting captain" so they can go to San Gill. Reese discovers he has been had and heads to San Gill as well. Unknown to all the three Rangers, there are two complications awaiting them in San Gill. One, that's where Capt. Parmalee went to give his speech. Second, there is a plot being hatched in San Gill to kill officials of the Mexican government.
—Bill Koenig