November 1941. Lieutenant Ralph Trewin, DSC, arrives at Singapore as second-in-command of the shallow-draught gunboat, "HMS Porcupine". To Trewin, still shocked from wounds received during the evacuation of Crete, the gunboat and her five elderly consorts seem to symbolise the ignorance and blind optimism he finds in Singapore. And the captain of the "Porcupine" is as unwilling as the rest to take heed of Trewin's alarm, for to him the gunboat represents his last chance.
The following month, the Japanese invade Malaya. In three months Singapore, the impregnable fortress, knows the humiliation of surrender. Through the misery and despair of this bloody campaign Trewin and his captain are forced to draw on each other's beliefs and weaknesses, and together they weld the little gunboat into a symbol of bravery and pride.