In an adventure that spans centuries, Captain Kirk fights alongside a U.S.S. Enterprise from the past to stop the devastating "Doomsday Wars" that should never have happened. In a universe forever changed by those events, the crew of the Enterprise must once again battle the powerful juggernaut known as the "Doomsday Machine." Guest starring Original Series alumni Barbara Luna, Malachi Throne. and William Windom as Commodore Matthew Decker.