Everyone has long been accustomed to the fact that, having decided to summon a demon, you knowingly sell your soul to the dark Forces. In fact, few people know that the challenge itself is quite innocent, and the soul is sold for benefits with which the demon will seduce you. Therefore, if you do not want to go over to the dark side, but you really need a demon (the roof is leaky, and there is no one to patch it up), there are several rules, following which, you can exploit the involuntary workforce in the person of a fanged demon with a clear conscience and not fear for your soul. Which is what I’ve done six times already. But in the seventh everything did not go according to plan on all counts at once...