TNG “Cause and Effect”. Definitely one of my favourite episodes of the series. I’d been finding season 5 a bit of a soapy and unambitious slog, but this is a high concept sci-fi story with guts and ambition, and the most shocking Star Trek teaser I think I’d ever seen. (Until Ichbeb’s eyeball gouging perhaps, but that was shocking bad). Jonathan Frakes’ directing is superb and helps keep the episode pacey and visually interesting while minimising the repetitiveness.