WilliamxGrell. What will William do if his crimson colleague falls ill? One-shot, Grelliam.

Both the Phantomhive household and the Shinigami Dispatch Society are struck dumb, as a strange series of murders occur that involves them both. The Phantomhive name is being threatened, and there are souls at stake. What kind of killer could have done all this? How is this even possible? Who will solve the mystery?