Simon Says... Die - Kate Morgan Thrillers, #9

Detective Kate Morgan arrives at a broken-down house, supposedly the site of a suspicious death, only to receive a screaming warning from Simon not to enter the building. Turns out, she had been given the wrong address but does find a dead body at the corrected address. As Kate sorts out whether she has a Black Widow on her most recent case, Simon tries to help a homeless man, who ends up in the morgue-now one of Kate's newest files because that poor man's body had been found in the broken-down house.
That's nothing compared to what else she finds on the premises. Kate's investigations into these deaths confirms the two properties have connections, including linking Simon to the haunted history of the broken-down house. When yet another homeless man is found dead at the broken-down house, Kate struggles to sort out the different threads, before the next man is killed-and this one might not be so homeless .