The B.P.R.D. (Bureau of Paranormal Research and Defense) is the organization started by Hellboy and this is the third softcover collection of the Plague of Frogs storyline collecting three B.P.R.D. trades.
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 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. This is the fourth (of four) softcover collections of the Plague of Frogs storyline each one collecting three of the original B.P.R.D. trades.