This episode really is something special. This is apparent right from the opening scene, which shows that David has done what viewers were probably wondering why he didn't do earlier: left civilization entirely, thus removing any chance of the Hulk doing harm. At least, that's the theory. The episode cheats in proving his theory wrong, since the trouble all starts with another fugitive, Dr. Gail Collins, just happening to stumble upon his hut miles deep in the Mexican woods. But that's okay; this episode is still unique and brilliant.
Dr. Collins is a famous neurosurgeon, and when a patient died on her table, she was charged with falsifying the patient's written permission to operate. Though innocent, guilt prompted her to flee. David refutes her guilt: "You tried to save her because you're a surgeon, and a human being. And you failed. Because you're a surgeon, and a human being." It's a great line, and it's doubtful that anyone could have delivered it as movingly as Bixby does.
Yet for once, David is not the pure righteous hero. He's right about Gail, but he's plainly a hypocrite in the matter, failing to acknowledge that he is hiding from his problems just as much as she. It also seems rather unfair that even after Gail spills her dark guilty secret, he still refuses to tell her about his being the Hulk. But does all of this make David even a bit less sympathetic? Nope. It just shows that like everyone else on the show, David Banner is a flawed human being in need of a little steering in the right direction.
The episode climaxes with another break from series formula: a long overdue demonstration that the Hulk *is* dangerous, a reminder of the price that will be paid if David doesn't find a cure for himself, and a message for us all that when we give up on ourselves, we often hurt other people as much as ourselves.