In response to a warning of great danger given by the White Guardian, the Fifth Doctor sets new co-ordinates and the TARDIS materialises on the heaving deck of an Edwardian racing yacht. But the Doctor soon discovers that this is no ordinary yacht-and no ordinary race. Captain Striker is competing for an unusual prize-"Enlightenment." The crew will be lucky to reach port safely-but with such a prize would they be lucky to win?