The Fifth Man (novel) - Plot Summary

Plot Summary

Eight months into their stay on Mars, the life-sciences specialist discovers a microbial fossil. Subsequent to this, the crew begin to suffer various mishaps, including damage to mission property and direct attacks upon themselves. Complicating the situation is the apparent psychiatric breakdown of the mission commander and his definite attempts to injure or kill his fellow crewmembers.

On Earth, the Mars Mission Director, working with an agent of the FBI, races to discover who sabotaged the mission before the crew even arrived on Mars—and who might be trying to strand the crew on Mars now that they're on it. He is shocked to discover that his own Flight Director committed the initial sabotage—he was trying to seed Mars with a bacterium that would be taken as evidence of life on Mars, thus ensuring continued funding of Project Ares, the official name for the program.

But when the life-sciences specialist falls ill from an actual microbial infection—from live bacteria which she has subsequently discovered—the mishaps multiply, with a corresponding increase in the physical danger to the crew. Someone other than the Flight Director is responsible for this. At the very end, that someone is revealed to be a NASA engineer who fears that the crew, now on their way back to Earth, are bringing back a germ that could potentially kill millions of people—this although the crew clearly showed that the germ was sensitive to the antibiotics they had carried with them. The mission ends with the psychiatrically challenged commander sacrificing his own life to save the rest of the crew—and the marriage of the two mission specialists aboard their Earth Return Vehicle.