Marooned on Mercury

When a distress call summons the crew of the Anastasia to the burning wilderness of Mercury, they are reunited with their old ally, Sondar. He tells them of the beleaguered Mercurians who are held in thrall to a cruel new taskmaster - the Mekon! The exiled Mekon is rallying his forces, plotting a desperate revenge against his former homeworld of Venus and his hated enemy, Colonel Dan Dare!