Originally the employer for the bulk of characters in the Hellboy series, once "Red" decided it best to go out on his own for personal reasons, the bureau didn't cease to exist. Just because George and Weezie moved on up to a de-luxe apartment in the sky doesn't mean that Archie and the rest of the Bunker clan disappeared. (For those who have no idea what I'm referencing, watch some Nick at Nite, if that still exists.) No, the rest of the supporting characters are interesting enough that, much like certain T.V. show casts, they deserved a spin-off. Think Angel, Torchwood, The Lone Gunmen, Joanie Loves Chachi. (Again, reference the internet for some of these; I'm an old man who has to take his pills and yells at kids playing on his lawn. It's hard being 31. Go fetch me some prune juice.)
To borrow a line from Billy Barty's character in the movie Willow, "Forget all you know, or think you know." If all you know of Hellboy or the B.P.R.D. is from the films by Guillermo del Toro, you might be slightly misinformed. In all honesty, I think he did a hell of a job with both films, but since the dawn of motion picture history, creative license has been taken when it come to films based on previously published literature. This is often done due to time constraints, trying to get the most concise story into a two-hour timeframe or simple ego mania. I've got my eye on you, Tim Burton. Bottom line, before forming an opinion, I usually do the following, which I can't suggest heartily enough. Go to the source material.
That being said, B.P.R.D. Plague of Frogs Volume 1 is an omnibus of Bureau information. Consider it a crash course in all things B.P.R.D. What's great about this omnibus is that it’s self referential with regard to the Hellboy stories that spawned this off shoot, so that even one who may not have even heard of Hellboy can get some of the inside jokes and references. More importantly, it defines how a group changes and grows without that lead figure being the center of attention. You think Ace Frehley doesn't want to shine on his own from time to time or is just happy letting Gene Simmons take the spot light every night? The B.P.R.D. explains how each member contributes to the group with their own personal skills, not just as back up for a main character. B.P.R.D. Plague of Frogs Volume 1 is a collection of the first three B.P.R.D. trade books, Hollow Earth & Other Stories, Soul of Venice & Other Stories, and Plague of Frogs, which actually started in the Hellboy series. Plague of Frogs, in fact, was an arc spanning 10 years, starting with Hellboy and ending with the B.P.R.D. It also reveals the origin of one Mr. Abraham Sapien, which is an interesting tale in and of itself.
The first of what will ultimately be 4 omnibi, B.P.R.D. Plague of Frogs Volume 1 isn't just a collection of trade graphic novels, but the journey it took to get there. With commentary by Dark Horse Editor Scott Allie, creator of Hellboy and the B.P.R.D. Mike Mignola, writers Scott Kolins and Michael Avon Oeming, artists Guy Davis and Cameron Stewart, and over 30 pages of original sketch art that became these fantastic books, it's a definite pick up. Unless you need to have each individual comic, trades are the next best thing, because they compile a number of those comics into one convenient book. That's where an omnibus out does even the longest graphic novel trade. These go to 11.