I really enjoyed this. Yes, it‘s a bit dry and pompous sometimes (I wondered if it was actually an Asimov pastiche that wasn‘t quite in the right key) and Rod Stirling‘s film adaptation made artistic choices that are more authentically sci-fi, but, within the franchise that it‘s still spawning, it earns its prototypical credentials as an enthralling adventure that‘s a thoughtful, moving critique of vivisection with a fine example of a twist ending