When Richard Mariner's tug Sisyphus is hit by a huge rogue wave off the Greenland coast, only superb seamanship and good luck save her. The vessels ahead of Sissy are not so fortunate and an ever-more desperate race begins as Sissy must pull the stricken submarine Quebec up towards the surface, and somehow keep her there as they battle towards their rendezvous with a rescue fleet at the southern point of Greenland the ominously named Cape Farewell.