Walking Dead: A Crime Novel (The James Pibble Mysteries)

This brilliant crime novel by CWA Gold Dagger winner Peter Dickinson is set in the Caribbean, where a researcher becomes trapped like a rodent in a maze

When it comes to his rats, David Foxe is an expert. He decides when they eat, when they exercise, when they take their medicine—and when they die. For the sake of the Company, he performs all manner of experiments on his helpless subjects, testing various drugs designed to improve the animals’ nature. After a particularly grueling series of tests, he is sent on a working vacation to the Southward Islands. This Caribbean paradise is ruled by the shadowy dictator Dr. Trotter, who is said to possess demonic power and whose mother is rumored to be a witch. Foxe may be a man of science, but he now finds himself in a world governed by the occult.
 
When a dead body is discovered in his island laboratory, Foxe becomes the key suspect and is taken prisoner. The only way to clear his name is to carry out experiments on his fellow inmates. Amid radical insurgents, crazed prisoners, and a crumbling dictatorship, Foxe must now escape this most dangerous experiment of all.