Frontier anarchy

An unlocked door, an unsolved case and an untold story. What happens when the past comes back?
22 years ago jack Simmons dad was shot, three times in the back of the head, executioner style. The suspect was never found, though rumours flew around of an uncle on the wrong side of the law there was never enough evidence. Present day and jack works as a cop. One day on duty jack responds to a call of a murder. This murder is Almost identical to the murder of his father, could it be a second round or a copycat? Jack has his suspicions. Never sharing them aloud, as over the course of two and a half weeks seven other identical cases happen. Though the last has a letter addressed to jack, containing an address and a key. Jack drives to the old abandoned house at the address and unlocks it. What's inside the house? , what's the killer hiding that he can only share with jack? , is the killer the same person who killed his father two decades before?