Now Nimoy and Bennett knew that their story would involve going back in time to retrieve humpback whales. But why? How would the whales be crucial to the future, at least in a metaphorical, science fiction way---that is, how would their absence create jeopardy?

The whale songs suggested that communication could be the key. Nimoy discussed extraterrestrial communication with scientists including physicist Philip Morrison and Frank Drake (whose Drake equation, suggesting the probability of intelligent life on other planets, was used in garbled form by Gene Roddenberry as evidence that the original Star Trek series wouldn't run out of new life and new civilizations to explore.) Morrison told him that space aliens would probably be so different that they couldn't physically speak our languages, and their modes of thought might be so different that there would be no common basis for communication.

Taken literally, that insight would end the Star Trek universe instantly. But the idea of radically different forms of communication suggested the possibility that extraterrestrials might find it easier to communicate with species on earth other than humans. Like whales, who had populated the oceans and presumably were singing their songs long before humanity existed, let alone learned to talk.

Then another element suddenly became central to Star Trek IV: Eddie Murphy, then Paramount's biggest box office star. He was a Star Trek fan and wanted to be in this movie. Using the basic elements of time travel and the whales, a script was written with Murphy as an oddball professor who helps bring Kirk's crew and the whales together, and winds up returning to the 23rd century with them, where he gets to don a Star Trek uniform. But Nimoy wasn't happy with the script, Murphy was interested in other projects, and Paramount may have thought twice about the idea as well. However it didn't happen, Eddie Murphy was gone from Star Trek IV, along with a lot of precious time.

Now the project was falling behind schedule. Nicholas Meyer, director of Star Trek II who had written the script for that film based on successful ideas in earlier rejects, and done it in record time, was asked to ride to the rescue as a writer. He agreed. Harve Bennett (who had written the script for III) would write the beginning and the end (the first and fourth acts), and Meyer would write the middle two acts, which took place in San Francisco. Nimoy also contributed dialogue.

Now the process of making the story real began: casting new roles, scouting and deciding on locations, designing and building sets, and designing and building...whales. Some existing footage shot by scientific expeditions of the normally camera-shy humpback whales was used, but all the rest of the whale footage was done with miniature models and larger replicas of the parts of the whale needed for shots in scenes with human actors. The models had to move naturally and a nearly life-sized piece of the whale had to mimic the motion of a whale's tail breaking the surface.

Industrial Light and Magic was assigned the task of creating the moving models, but got some unexpected assistance from...a humpback whale. The two whales in the story had wandered into San Francisco Bay and were being kept at the fictional Cetacean Institute in Sausalito. But as ILM began their task, a real humpback whale did wander into San Francisco Bay. He stayed around long enough for a camera crew to get some film footage. It wasn't good enough to include in the movie, but the ILM team was grateful nonetheless. There was so little reference footage of these whales in action that they studied it and found it useful for designing their models.

The miniatures and larger models, together with how they moved, and were painted, lit and filmed, were so convincing that after the movie came out, some environmentalists called Paramount to protest that the filmmakers must have harassed the whales to get that close. It was the rare situation of filmmakers ecstatic about getting complaints.

He'd done a lot of work already before filming started, but when it did, Leonard Nimoy knew he'd been successful so far: he had something. Paramount executive Ned Tanen met with him after reading the shooting script. "This script is wonderful," he told Nimoy. "It's so wonderful, even if this wasn't Star Trek, we would make this picture."

"I said 'thank you very much,' I tucked it under my arm," Nimoy recalled, "and went off to work to shoot it...Shooting it was a joy."