The Federation faces economic and political collapse, a situation the Klingon Empire is all to willing to exploit. Klingon Captain Kargh attacks one of the Enterprise's shuttles as it ferries Federation Ambassador Rayna Morgan to the ship from the neutral planet Babel. After chasing off the attacking Klingon vessel, the Enterprise sets course for Earth. En route, she is attacked by a different Klingon ship and badly damaged. As a result, Chekov is irradiated, which activates a medical condition that causes him to age rapidly, and McCoy cannot find a cure. While Chekov, with Ambassador Morgan's help, comes to terms with his impending death, Kirk must work with the same Klingon captain he confronted earlier to discover who is behind the second attack, and save his ship, and possibly the future of the Federation itself.
—Greg Price