From the introduction:
The world you are about to enter is much like our own - or at least, that’s what most people would tell you. Behind the veil of normality, the supernatural exists- unseen by most- the knowledge of its existence safely guarded and protected for fear of what could happen if the truth got out. The Bureau of Paranormal Research and Defense (or BPRD) is the foremost of these protectors; an agency formed by Roosevelt during World War Two when it seemed like Hitler would seize victory in the war, due to his use of occult artifacts. And the most well-known (to the chagrin of his superiors) of these agents is Hellboy; a demon with a red right hand who has been prophesied to bring about the end of the world. Hellboy will face many threats during your time here; in addition to his normal operations, he’ll have to deal with a mad Russian sorcerer trying to get him to fulfill his destiny, bringing his dark god to earth, and an Elvish prince trying to wipe out humanity. Whether you decide to help him or not is up to you.