Burden the Hand by Randall Garrett

When the wealthy heiress Nikki is held captive in her own home by the villainous lawyer Van Ostrand and his henchmen, things look dire. But unbeknownst to them, Nikki's long-lost father, a brilliant scientist, has a plan. By taking over the body of the housecat, he spies on the criminals to uncover their plot. Will he be able to save his daughter without blowing his cover?