In the heart of Edinburgh, a killer leaves a trail of secrets carved in blood.

As the leader of the Serious Crime Unit, DCI ‘Mac’ McNeill is no stranger to the city's darkest secrets. But when a body marked with Celtic symbols is discovered in a run-down tower block, the case challenges even his seasoned instincts.

With the victim's ties to the treacherous drug scene and a notorious crime lord complicating matters, Mac seeks the help of Dr. Clio Wray, an expert in ancient symbology.

But when a second body emerges, an unsettling connection is made to Mac himself.

The case spirals into uncharted territory.

The gripping first instalment in the DCI McNeill crime thriller series.