Where There's Smoke by Penny Grubb
Private investigator Annie Raymond is now working in London, on a case that has suddenly turned nasty, when she's asked to travel back to East Yorkshire for another outing with the Thompson sisters. But no one wants her there, and the man whose signature is on the paperwork is in hospital fighting for his life. When someone gets to Barbara Thompson before Annie can clear up the confusion she realizes Barbara was playing a dangerous game. And that now it's too late to walk away, and save herself. The fourth outing for PI Annie Raymond sees her pick her way through a minefield of double-dealing and return to a past she thought she had left well behind.