But the Bird of Prey carries a dangerous cargo, a deadly force that is soon unleashed in the heart of the Federation. Suddenly, the only hope for the Federation's survival lies buried in the tortured memory of Commander Spock's protege, a cadet named Saavik. Together, Spock and Saavik must return to the nightmare world of Saavik's birth -- a planet called "Hellguard, to discover the secret behind the Romulans' most deadly threat of all...