Amanda Pitt is a detective investigating an unidentified dead body found by the Forth and Clyde canal. Martin McGregor is a computer expert who discovers a credit-card skimming operation on his doorstep and decides to investigate. Their investigations turn out to be linked, and involve international sex trafficking. Meanwhile, a failed newspaper reporter is investigating historic gang activity in Glasgow. He suspects that Amanda and Martin were involved, and he's right. They have to uncover the secrets of other people while closely guarding their own. Helping Martin is a teenager, Michael, who is part of an international vigilante online group called 1794. Through them, he is danger of finding out rather too much about Martin.