[Constellation Auxiliary Control]
KIRK: Did you run a scanner check on it? What kind of a beam?
DECKER: Pure antiproton. Absolutely pure.
KIRK: (answers communicator) Kirk here.
SPOCK (OC): Spock here, Captain.
[Enterprise Bridge]
SPOCK: Unable to raise Starfleet Command due to heavy subspace interference.
[Constellation Auxiliary Control]
SPOCK (OC): Attempting to remedy.
KIRK: What about the Constellation's tapes?
[Enterprise Bridge]
SPOCK: She was attacked by what appears to be essentially a robot, an automated weapon of immense size and power. Its apparent function is to smash planets to rubble and then digest the debris for fuel. It is, therefore, self-sustaining as long as there are planetary bodies for it to feed on.
[Constellation Auxiliary Control]
KIRK: A robot weapon that purposely destroys entire solar systems. Why?
[Enterprise Bridge]
SPOCK: Unknown, Captain. However, Mister Sulu has computed the path of the machine, using the destroyed solar systems as a base course. Projecting back on our star charts, we find that it came from outside, from another galaxy.
KIRK (OC): What is the projected course of this thing?
SPOCK: If it follows its present path, it will go through the most densely populated section of our galaxy.
[Constellation Auxiliary Control]
KIRK: Thank you. Stand by, Mister Spock. Kirk out.
MCCOY: This whole thing's incredible. A robot? A machine like that, who would build it?
KIRK: We don't know. An alien race, apparently from another galaxy.
MCCOY: But why?
KIRK: Bones, did you ever hear of a doomsday machine?
MCCOY: No. I'm a doctor, not a mechanic.
KIRK: It's a weapon built primarily as a bluff. It's never meant to be used. So strong, it could destroy both sides in a war. Something like the old H-Bomb was supposed to be. That's what I think this is. A doomsday machine that somebody used in a war uncounted years ago. They don't exist anymore, but the machine is still destroying.
DECKER: Oh, forget about your theories! That thing is on the way to the heart of our galaxy. What are you going to do about it?