Cassius was a truly exceptional police dog whose career became the stuff of legend and the gold standard for all dogs coming after. In just five years he scored a century of arrests, saved lives, bit half a dozen policemen, and gave his handler, PC Joe Sleightholm, the most exciting, exhilarating, and nerve-wracking times of his life. Things did not go according to plan in Sleightholm's first years as a police dog handler. The difficulties of finding and keeping the right dog were so great that he was ready to give up. Then Cass came along. The two of them quickly formed a bond, graduated as stars from the training school, and became an outstandingly effective working partnership. Cass became part of the Sleightholm family, too. Car thieves, armed robbers, drug dealers, murderers, burglars, Cassius learned to find them, contain them, intimidate, and attack if he had to. Sometimes it was dangerous for him. Usually it was more dangerous for the criminal. The story of Cassius is by turns thrilling, funny, and moving, and always a fascinating insight into the freemasonry of police dog training.