After a work accident renders him an amputee, Jim returns to work at the railroad station in South Africa. He does the best he can, but the work is difficult without both his legs. One fateful day, Jim meets Jack, a smart baboon. Together, they develop a friendship. Jack, the baboon, quickly learns to run the switch system for trains, which worries passengers. Jim must prove that his baboon is smart enough for the job or will lose his job.