The Tomol are a primitive civilization occupying a lone island on a remote world. Their culture is an enigma, centered on every member's commitment to a painful, fiery self-sacrifice upon reaching maturity. But one of their clan has shunned this obligation, triggering a transformation into a new, powerful life form. Answering the distress call of the U.S.S. Sagittarius--which has crashed on the planet following a fierce battle with the Klingons--Captain Atish Khatami and the crew of the U.S.S. Endeavour must now attempt a rescue mission...even as they are locked in battle with the evolving, increasingly malevolent Tomol who, if allowed to escape their home world, pose an imminent threat to the entire galaxy.