Chief Inspector Sheehan and his team have never encountered a case like this, and it's taking Belfast by storm.

Sheehan is no stranger to serial killers, vicious psychopaths, religious fundamentalists, and more. But when members of a coven start turning up dead all over Belfast, Sheehan and his Serious Crimes Unit are faced with a level of evil beyond anything they have ever experienced.

To make matters worse, when they discover a malevolent Satanist — supported by a powerful demon — is setting the stage for a human sacrifice, the team is thrown into the unknown.

The clock starts ticking as the sacred Celtic feast of Lughnasa fast approaches. Can Sheehan discover who is murdering the coven and rescue the young woman who has been abducted for a human sacrifice before it's too late?