Will they end up killing one another? That's what concerns the authorities as much as the scientific and technical hurdles of sending folk to Mars. So they address the human issues, as they would in an army, by appointing a chaplain.
The Church of Scotland considers this post just right for Steve McKay, one of their more wayward recruits. Steve finds he is off to a parish more remote and barren than he had ever imagined. However, he discovers that the remoteness creates a heightened awareness of the meaning of life and they share some Earth-shattering revelations.
Deep thinker he may be, but Steve is no saint. He muddles through offering his brand of care and support, both in the chaplaincy and increasingly in the Mars Bar. A misdemeanour on his part finally leads to Life on Mars in a way unforeseen by the authorities.