Ronald Carpenter (the narrator) is a zookeeper that gets help from a company called The Eclipse when he needs to recapture some escaped animals. The company takes a shine to him and lures him into working for them. They are keeping a zoo of animals that they use for medical testing and are happy to have his expertise in accommodating them. To prove his loyalty they have him come along to take the scientist Nigel hunter captive.
Ronald and Nigel come to find out that the creatures kept by The Eclipse are supernatural animals that the average person would not consider real. The Eclipse is keeping `fantasy creatures for testing because they have no legal protections and many of them, like werewolves, are nearly human.
Now the story is from Nigels point of view and the time is set back to a little before he was taken captive. Nigel Hunter was working for a lab owned by The Eclipse, but his test animals were rats and he is unaware of the supernatural testing. After an accident, he decides to test a procedure that allows great speed on himself. The rats with the increased speed begin to die off. The Eclipse higher ups decide that Nigel is as good as a test animal and get Ronald to take him captive.
Being held with the test creatures, Nigel becomes friends with the beings he is kept among as he is basically tortured by Eclipse folk who want to see the impossible speed. He and friend creatures decide that he is fast enough to possibly escape and get help to stand against The Eclipse.