Third-billed Lee Marvin dominates the proceedings in A Life in the Balance. Marvin plays a psycho killer, whose trail is dogged by inquistive young Jose Perez. Jose's father, musician Ricardo Montalban, has been accused of a series of murders. The boy is convinced (correctly, it turns out) that Marvin is the guilty party, and trails the man in hopes of bringing him to justice. No dummy he, Perez leaves a trail for the authorities to follow--a series of smashed-up police call boxes (a similar plot device was deployed for comic purposes by Harold Lloyd in Professor Beware). A Life in the Balance was filmed on location in Mexico City, with a great deal of screen time devoted to a colorful carnival.