 In orbit , the undermanned Enterprise is attacked and disabled by Kruge . In the standoff that follows , Kruge orders that one of the hostages on the surface be executed . David is killed defending Saavik and Spock . Kirk and company feign surrender and activate the Enterprise 's self @-@ destruct sequence , killing the Klingon boarding party while the Enterprise crew transports to the planet 's surface . Promising the secret of Genesis , Kirk lures Kruge to the planet and has him beam his crew to the Klingon vessel . As the Genesis planet disintegrates , Kirk and Kruge engage in a fistfight ; Kirk emerges victorious after kicking Kruge off a cliff into a lava flow . Kirk and his officers take control of the Klingon ship and head to Vulcan . 
