KIRK: Spock?
SPOCK: As suspected, the Probe's transmissions are the songs sung by whales.
KIRK: Whales?
SPOCK: Specifically, humpback whales.
McCOY: That's crazy! Who would send a Probe hundreds of light years to talk to a whale?
KIRK: It's possible. Whales have been on Earth far earlier than man.
SPOCK: Ten million years earlier. And humpbacks were heavily hunted by man. They've been extinct since the twenty-first century. It is possible that an alien intelligence sent the Probe to determine why they lost contact.
McCOY: My God!
KIRK: Spock, could the humpback's answer to this call be simulated?
SPOCK: The sounds, but not the language. We would be responding in gibberish.
KIRK: Does the species exist on any other planet?
SPOCK: Negative. Humpbacks were indigenous to Earth. Earth of the past.
KIRK: Then we have no choice. We must destroy the Probe before it destroys Earth.
SPOCK: To attempt to do so would be futile, Admiral. The Probe could render us neutral easily.
KIRK: But we can't turn away! ...There must be an alternative?
SPOCK: There is one possibility, but I cannot guarantee its success. We could attempt to find some humpback whales.
McCOY: You just said there aren't any, except on Earth of the past.
SPOCK: Yes Doctor, that's exactly what I said.
McCOY: Well, in that case... Now wait just a damn minute!
KIRK: Spock, start your computations for time warp. ...Bones, you come with me.