Roisin Doyle is becoming increasingly despairing and angry at the behaviour of her literary agent husband Graeme in middle-class Dublin. It is not so much his affairs that angers her but the fact that she also discovered that he has been systematically stealing from her too. It appears his agency is not doing too well.
But not content with stealing and cheating, her husband has also resorted to systematically poisoning her after she locked him out of her bank account. The realisation stuns her, and she decides to act.
What husband Graeme does not know is that Roisin has a chequered and secret past because she was once a notorious activist towards the end of the Troubles earning herself the soubriquet of 'The Angel of Death'.
She decides on a drastic plan to spike a bottle of wine with a powerful sedative and to engineer a gas leak that will result in a massive explosion when he and his mistress are at their house one night. While they are both unconscious, she removes all identification from the woman and becomes Maggie Taylor.
She starts a new life in Liverpool where she gets a job at the University of Liverpool. It is there that she meets and befriends Naomi and Emma but her past catches up with her when she receives a note from Finley Starr, a colleague from 'the old days' saying that he knows who she really is. But Finley and his gang implicate her in the murder of a Chinese student who is also suspected of being involved in Chinese state spying at Liverpool University.
There are two further murders in Liverpool masterminded by Starr and his lieutenant Tommy O'Connor and Maggie decides to target him first and prove his guilt, clearing her name in the process, but he twice manages to escape.
It all comes to a head when Starr and O'Connor abduct Maggie's friend Emma and threaten to kill her if Maggie does not surrender herself to them. Starr chooses Liverpool's 'bombed-out' church, a reminder of the 1941 Blitz, for the meeting at midnight.
The church is the location and setting for a bizarre and eerie art installation of alabaster statues in grotesque positions, one of which is Maggie. Her other friend, Naomi, goes on her own but not before alerting the police. After Tommy produces Emma, shots ring out and Tommy is killed but Finn escapes before the police arrive in force.
Maggie has also escaped and returns to Dublin, planting incriminating evidence which points to Finley's culpability for the murders of Graeme and Roisin Doyle.
The final chapter takes place on the Liverpool to Dublin ferry where Finley is arrested by detectives from the Gardai and handcuffed and locked in his cabin.
When they arrive, Finley has mysteriously died. Later, a small hole is found above his heart. Maggie, who always has a hidden foot-long hatpin concealed somewhere, was not found on the boat despite every passenger being questioned.