Step into Chaos — William Shatner

After defeating the dreaded Hunzza fleet, Jim Endicott wants a "normal" life. But his wish is not to be, for a new and even more terrible conflict is stirring. Earth's former ally, the Alba Packlord, suspects that humans are about to "Leap"--transcend to another level of existence in a process that will sweep away star systems, laying waste to the universe. To eliminate the human threat, the Packlord has made a secret alliance with the Hunzza--but not if the mysterious immortal known as the Outsider can stop them using Jim as a weapon. First, though, the Outsider has to find the embittered hero. Distraught over the death of his father, Jim has plunged deep into the underground, where danger of another kind lurks in the shape of a girl as bad as she is irresistible. But the Packlord will stop at nothing to succeed, including assassination. Jim's only hope for survival lies in making the Leap himself: taking the step into chaos that will save humankind or turn the universe into a graveyard of burned-out stars.