B.P.R.D: Plague of Frogs Hardcover Collection Volume 4

This is a story that began in the first issue of "Hellboy" concludes with the B.P.R.D. team set to permanently wipe out the subterranean colony of frog monsters. The team tracks down the Memnan Saa's hideout, but soon find themselves in over their heads when old enemies like the Black Flame arrive to lay waste to the world!