The book starts when Lucy fishes a body out of the River Foyle. The River Foyle is a river in west Ulster in the northwest of the island of Ireland, which flows from the confluence of the rivers Finn and Mourne at the towns of Lifford in County Donegal, Republic of Ireland, and Strabane in County Tyrone, Northern Ireland. From here it flows to the city of Derry, where it discharges into Lough Foyle and, ultimately, the Atlantic Ocean.
There are references to riots in Belfast throughout the book. Lucy watches the news on which she sees the protests of royalists because of some parades, and ACC Wilson keeps saying that they are short-staffed as many uniforms have been sent to Belfast. This took place in the summer of 2014.
There is a mention of the Fleadh, an annual celebration of Irish music. The Fleadh Cheoil is an Irish music competition. There are various stages to the competition. In Ireland there are county and provincial competitions leading to the All-Ireland Fleadh. In Britain there are regional, then national stages of qualification for the All-Ireland.
When Lucy tries to find Aaron and sees his house full of magazines of horses, she is told that Aaron used to work in the Queen’s stables, but he quit after the Hyde Park bombing in 1982. The Hyde Park and Regent’s Park bombings occurred on 20 July 1982 in London. Members of the Provisional Irish Republican Army(IRA) detonated two bombs during British military ceremonies in Hyde Park and Regent’s Park, both in central London. The explosions killed 11 military personnel: four soldiers of the Blues & Royals at Hyde Park, and seven bandsmen of the Royal Green Jackets at Regent’s Park. Seven of the Blues & Royals’ horses also died in the attack. One seriously injured horse, Sefton, survived and was subsequently featured on television programmes and was awarded “Horse of the Year“.