B.P.R.D.: Plague of Frogs Volume 1;

In 2001, Hellboy quit the B.P.R.D., leaving Abe Sapien, Liz Sherman, and a bizarre roster of special agents to defend the world from any occult threats, and the growing menace of the frog army.
Mike Mignola and Dark Horse present the complete Plague of Frogs saga in four volumes, from Hollow Earth to King of Fear. This first book explores the Bureau for Paranormal Research and Defense after Hellboy's departure, cracks open the secrets of Abe Sapien's origin, and sets the war on frogs in motion.