One week David's assisting at car races, the next week it's horse races. Will the next episode be about a marathon runner? Seriously, you'd think they'd avoid putting two episodes like "Ricky" and "Rainbow's End" one after the other.
Anyway, this is a pretty routine episode. David's interested in the titular racehorse because his trainer has brewed up a Native American Indian herbal concoction which turned him from a dangerously feisty mount to an even-tempered, potential champion steed. Female eye candy comes in the form of a hopeful jockey. Danger comes in the form of the jockey's pop, who holds a grudge against the owner of Rainbow's End because a patent he sold him a while ago turned out to be more lucrative than he thought.
There's enough intrigue to pull you along through the episode, but once it's over, I realized that the intrigue didn't amount to much in the end, and what it did amount to was left without explanation. We're never given a real sense of why the jockey's father would go to criminal lengths.
For that matter, we're never given enough on the jockey to care about her, and the herbal concoction simply has no effect. It doesn't make David's transformations change, or make the Hulk any different, or anything. This is, in sum, an episode full of ideas that aren't given a proper beginning, middle, and end. It doesn't even explore how the jockey deals with the fact that her father is a dangerous lunatic.