After several months' heavy war duty, the crew of the British submarine Sea Tiger is enjoying a much-deserved leave, when suddenly they're called back to active duty. Sub commander John Mills has been ordered to pursue and sink the formidable German battleship Brandenburg. A series of nailbiting seaborne perils, each one more life-threatening than the last, awaits the Sea Tiger as Mills endeavors to carry out his orders. Setting the British We Dive at Dawn apart from the usual Hollywood submarine epic is the fact that all the characters-include the senior officers-are between the ages of 19 and 23; There's no room for an "old sea dog" Alan Hale or Charles Bickford in this one. Though modestly produced, We Dive at Dawn offers a million dollars (or a million pounds)' worth of pulse-pounding excitement.