The Shadow People: Patel and Pardoe, Book 3

Jerry Pardoe and Jamila Patel hunt down a ritualistic cult inspired by Neolithic cannibals in the new chilling horror from Graham Masterton.
Det. Sgt. Jamila Patel and Det. Con. Jerry Pardoe have reluctantly acquired a reputation in the Metropolitan Police for their ability to tackle bizarre and apparently supernatural crimes. Now they have been called back together after three bodies are found in a London basement... bodies which have been taken apart, roasted and eaten.
The markings on the wall suggest this might have been done by some kind of religious cult – and as more people are kidnapped and cannibalised, Patel and Pardoe realise they are dealing with a group of devil-worshippers invoking an ancient god who has not been worshipped since the Neolithic age...