Glasgow PI Grant Cairns is asked to investigate a company called Caledonia Data (CalDat) which is suspected of being a conduit for dark money and fake news. As he follows a lead, he finds himself linking with an old colleague, ex-DS Amanda Pitt, who has become obsessed with explaining a murder at a Glasgow hotel, where the murderer could not possibly have known the victim and who died at the scene.

The two of them find their investigations are linked, and that an online hate campaign against an MSP could have fatal consequences for her.

Meanwhile, Martin McGregor's past life comes back to haunt him, and the world of online abuse becomes very personal for him.