From Thriller Picture Library #387, November 1961. Reprinted as Death Deals A Joker in #7, October 1966.
Someone in the Ralph Martin Motor-racing team is not playing nice and that puts the main driver in grave danger. Martin sends an urgent telegram to John Steel asking him to help by flying to Santa Carona in Mexico where the next race is scheduled for the next week. As cover he hires Riff and his jazz band from the coffee-shop below his office to travel with him.