After a breakthrough in an investigation, Alex McEwan finds the address of his old lover - carved into the flesh of a murderer. While researching a book on Scottish Masonic buildings, Kate Harlow - McEwan's lost love - has become involved with the occult underground, and powers beyond her comprehension. Kate's occult mentor has a devious plan, and to him, Kate is just a tool. Meanwhile, other shadowy figures of Scotland's occult underground have their own agenda. Alex and Kate race against time to prevent the fallen angels from heralding the Apocalypse. But are they already too late?