On patrol, the USS Excelsior, commanded by Captain Hikaru Sulu, is slammed by a shock wave traveling through space. Investigation shows that the wave came from Klingon space. The Klingon homeworld of Qo'noS (pronounced Kronos) is thrown into turmoil after the explosion of their homeworld?s moon, Praxis, a key Klingon energy production facility, damages their homeworld?s atmosphere. Estimates are made that the accident will have depleted the Klingon Homeworld's atmosphere in 50 years. No longer able to maintain a hostile footing, the Klingon Empire sues for peace with the Federation. Starfleet chooses to send the USS Enterprise to meet with Chancellor Gorkon and escort him to negotiations on Earth, a decision that doesn?t sit well with Captain James T. Kirk, whose son David Marcus died at the hands of Klingons, defending Lieutenant Saavik in Star Trek III: The Search for Spock.