Doctor Moreau has gone really gone off the deep end… and landed on his own private island. Moreau is a disgraced scientist who was booted out of London because of a little project that came to be known as the "Moreau Horrors."
Turns out the dude is a vivisectionist—"vivisection" being that fun family activity of experimenting on animals while they are still alive. Blegh. No wonder that when our poor narrator, Prendick, lands on the island his first thought is "Where is the nearest exit?!"
Moreau has managed to set up shop again on an island on which he's still engaging in vivisection, now trying to humanize animals—to literally pull the animality out of them, or inject the human into them. Unfortunately his science isn't the best, and a lot of grotesque and messed up test subjects inhabit the island—fearful of Moreau and his underlings.
Animal theorists are fascinated by this novel because it provides us with a look at Victorian ideas of what makes humans both human and animal, and also because the Doctor's work is so obviously freighted with a lot of symbolism and metaphor. For instance, one animal theorist has read the novel as a way to think through contemporary science's role in telling us what animals are and what we can learn from them.