This one opens with a generic (though beautifully filmed) horror movie sequence: Some naughty teenagers are driving through a storm when their car breaks down, they wander into the abandoned house nearby and split up (because hey, why not?), and one of them is gruesomely murdered. The story picks up a year later with David looking into the house's late owner, a brilliant radiologist who he suspects turned himself into the Hulk-like creature who manifested in town after one of his experiments. And the more David investigates, the more he finds to suggest that the radiologist found a cure for himself before he died.
This is a solid hook, and writer Andrew Schneider provides enough twists and characterizations to make this a satisfying episode on its own rather than a drawn-out teaser for part 2. The one minus is that the murder of the teenager is never explained, neither here nor in part 2. We learn who killed him, but not why, and the killer had no conceivable motive.
The final twist deserves special mention, since though the episode provides a less-than-subtle hint to it early on, it really hits hard. Yet even this is inevitably overshadowed by the debut appearance of the TV Hulk's first superpowered foe. The creators spared no expense on this ugly, with an utterly horrifying transformation sequence, posturing which recalls the Hulk's own muscle-flexing, and even a warped rearrangement of the Hulk's musical theme. As the episode closes, you really can't wait to watch part 2 so you can see the two superbeings meet.
An all-around excellent mystery with answers which are both satisfying and startling, this episode is definite must viewing, and provides the framework for its sequel installment, which is even better.