This is one of those episodes that most crime or adventure shows seemed to do, sooner or later, back in the 60's/70's, with one of the main characters alone, trapped, and pitted against an unknown tormentor. "Voyage to the Bottom of the Sea", "The Avengers", and "Charlie's Angels" are just three programs that come to mind right off the top of my head that did this. Not really a "bottle" episode, so to speak, since there are frequent cutaways to other locations showing what the rest of the team is doing, but very nearly so, w/ most of the action taking place in the darkened HQ. This one is fairly good, as these things go, and of course the Chief's disability adds a little bit to the sense of jeopardy. Still, the villain's whole deal left something to be desired. And, I felt somewhat cheated, because the idea that you're going to see Ironpants take a bath is dangled in front of you but never materializes. Rats.