Plot: Investigating the disappearance of homeless men, a disguised Bruce Wayne is knocked out. He wakes up in a prison camp with no idea where, or who, he is.
Stylistically, The Forgotten is a sharp change of pace for the Animated Series. From the harmonica opening, the sun-drenched, sweaty setting for most of the action, and the lack of a supervillain, the episode plays like an episode of something that'd be called "Cool Hand Bruce."
Set-up-wise, it's very similar to The Underdwellers, with a villain who exploits the weakest in society, trading orphan children for homeless men. But the Sewer King is a supervillain, with a costume and alligator henchmen. Boss Biggis (named only in the credits) is a disgusting, hypocritical human being who spits chicken flecks while complaining that his prisoners/slaves are too lazy, but otherwise employs traditional weapons like barbed-wire and guns.
Hence, I have a real problem with this plot hinging on the hoary cliche of concussion-induced amnesia, even if it does lead to some trippy visuals as Bruce Wayne puts his personality back together from fragments (and for a show that was never supposed to be about Bruce's origins, the Waynes have appeared in one out of four episodes so far, which is as many as the Joker).
Amnesia is such lazy writing, that handicaps the hero in a way that wouldn't actually work if you thought about it (wouldn't he lose motor skills along with his memories?). Maybe it's supposed to give Bruce time to bond with Salvo and Reilly before escaping, but Bruce could have just as easily just been trying to stay in-character while he waited for Alfred to show up, or actually handicapped with a broken-leg, or something besides stupid, stupid amnesia.
(At least when the new Batman: The Brave and the Bold cartoon did the same plot, Bruce loses his memory while in disguise, it led to a song and dance number.)
There are some good elements around the stupid, stupid amnesia. The painters do a fine job with the warmer color palate the sunny desert setting provides, and Shirley Walker shifts the score to the prison movie mood while still remaining in the Animated Series ouvre. And it's fun seeing both Batman and Alfred act as detective.
Alfred definitely shines in the episode, rolling around a scrap yard in his butler tux, and flying the Batwing to the rescue (and Bruce's surprise). I think it's hilarious that Alfred thinks to change out of his tuxedo when flying a plane, but still wears a bow-tie, and that he apparently set the computer to "snarky", which actually says "Your funeral" in response to the order to land.