The year is 1951.
This creature was developed as a secret side-project while designing uranium and thorium powered reactors in pursuit of new, alternative sources of energy. It wasn't long when scientists discovered that a human body contains wast amount of energy, enough to power small city for a whole year. This type of energy can be accessed, condensed and extracted by the Grimataur in a form of "Soul", a nickname given by scientists themselves.
Rumor has it, the creature was unleashed on purpose to roam the US farm lands and secretly harvest unsuspecting humans, away from well populated areas.
Remote farms is preferred habitat for Grimataur. It usually dwells in large barns, any obscured outbuilding or ponds if it has to.