When medical Dr. John Naysmith reports to his new assignment on Mars, he's immediately confronted by a crisis: the outbreak of an alien virus among several men who've been exploring the Martian landscape. The entire base is quarantined, and the Security Chief tells Naysmith that he has just 72 hours to find a solution, or the base will be destroyed by nuclear bombs to prevent the infection from spreading. With time running out, there's just one more option: visiting the crater that's the source of the infection. Can the doctor develop a vaccine in time?