The Summoning — E.E. Richardson

Justin hasn't ever really believed in the occult, even though his Grandpa Blake is an expert on the subject and has many tattered books on magic. But late one night, after stealing one of his granddad's books, he and three companions summon Dracherion, a malicious and dangerous spirit bent on revenge for being imprisoned in the ancient book. It's a race against time to find a way of banishing the spirit out of this world. But how do they do that when one of them can't be trusted?