The Burning Boy by Nicola White

Dublin 1986. The murder of an off-duty officer in Phoenix Park should have brought down the full power of the Dublin police force. But Kieran Lynch was found in a notorious gay cruising ground, so even as the press revels in the scandal, some of the Murder Squad are reluctant to investigate. Only Detectives Vincent Swan and Gina Considine are willing to search out the difficult truth, walking the streets of nighttime Dublin to find Kieran's lovers and friends. But Gina has her own secret that means she must withhold vital evidence. When a fire rips through Temple Bar and another man is killed, she must decide what price she is willing to pay to find a murderer.

Vincent Swan #3