Richard Wilson and Simon Callow star as two ageing astronauts on a perilous mission to a faraway planet, battling with loneliness, isolation, and occasionally each other. It is the distant future, and mankind is in need of desperate measures to ease the swelling overpopulation of earth. The solution; send elderly volunteers - men and women who would rather die alone on a distant planet than live out their last years in nursing homes - to prepare new worlds for human settlement. On board the star-ship, our intrepid space travellers contemplate the enormity of their mission, the importance of purpose, and even the definition of life itself.