Reserved for the Cat ~ Mercedes Lackey

This is book #5 in the Elemental Masters series. Ninette is a ballet dancer in Paris, who, when suddenly fired from her position, discovers that her cat can talk, and he promises to see that she is taken care of, if only she does as he says. The cat leads Ninette out of France and into England, where he instructs her to play the part of a famous Russian ballerina, who has been shipwrecked. Things seem to be going well, when suddenly it seems like someone is out to get Ninette, now known as Nina, and they have to figure out who is trying to kill her, and why.