Kick Back by Val McDermid

Manchester private eye Kate Brannigan has her hands full investigating a bizarre series of white-collar scams involving missing conservatories and fraudulent land deeds. The stakes turn intensely personal when she realizes the sophisticated property racket has ensnared her close friends, lesbian couple Alexis and Chris, threatening their financial security. As Kate digs through layers of crooked lawyers, double-crossing siblings, and forged paperwork, she finds herself up to her neck in a deadly corporate conspiracy where the perpetrators are willing to resort to murder to protect their illicit windfall.