"Where No Man Has Gone Before" really set the tone for the "Star Trek" series more so than even Rodenberry's original pilot, "The Cage". In this story we have Kirk forced into making agonizing life and death decisions/his close relationship with Spock and that character's adherence to total logic at times being compromised by his own human side/the heroic crew all game to explore the vast uncharted regions of space- it's all there like a blueprint for numerous "Star Trek" scripts that followed.
When Kirk's friend Gary Mitchell is endowed with astonishing powers of ESP and telekinesis, Kirk and Spock grow alarmed as he starts to test his ability to take over the Enterprise. Spock urges Kirk to maroon Mitchell on Delta Vega, an uninhabited planet. At first Kirk is outraged at even the suggestion, but eventually accepts the cold logic of this solution as Spock warns him, "we'll never reach another earth base with him on board."
The scenes charting Mitchell's evolution are well acted by Gary Lockwood. His personality shifts startlingly back and forth between the affable crewman he was and the detached mutant he is becoming, and these glimpses of Mitchell's former self help us retain a measure of sympathy for him. He, too is a victim in this story.
The silver contacts Lockwood wears are especially effective at making him appear as if his newly acquired powers have rendered him aglow from within. Plus, an echoing quality in his voice makes statements like "You Should Have Killed Me When You Could, James" sound especially frightening.
One of the episode's best scenes occurs when Mitchell, severely weakened after trying to break through a force field, returns momentarily to his old self. A few seconds later however, the glow in his eyes re-ignites, but now it's even brighter than before. As he slowly rises to his feet, it looks this time like he will be able to pass right through the force field. But instead Mitchell stops and with a smile calmly informs them, "I just keep getting...stronger. You know that, don't you?" It's superbly intense and Alexander Courage's terrific music adds just the right note of dread to this scene.
Of course Mitchell does eventually escape, taking the ship's psychiatrist, Dr. Daner, (played by Sally Kellerman) with him. She had also been affected by the mysterious force that has altered Mitchell and now they both have become mutants. Kirk bravely sets off on his own to track Mitchell down before his powers become so great no one can stop him.
I gotta say, even after 40 years, all the elements of this one still work. From the threat imposed by Mitchell's ever increasing powers to the agonizing questions it poses about what to do with him, and finally the physical conflict between Kirk and Mitchell at the end. Oh, and also the moment Dr. Daner must choose a side; it ALL works so well. James Goldstone deserves particular praise for his sure handed direction and this is certainly right up there with his excellent work on the original "Outer Limits".
I suppose "Trek" purists might criticize certain things like Mr. Sulu's then uncertain role on the ship and the moment where Spock actually smiles, but one must keep in mind this was only the second episode ever filmed, so the characters were still evolving. Anyways, such minor nitpicking's really don't detract from the obvious strengths of this superior entry in the series. I would place "Where No Man Has Gone Before" among "Star Trek's" four best episodes. It's a smart and thoroughly entertaining example of television science fiction done right.
