Sinister - Abigail Lynne

Leighton Connors is losing her mind. Or at the very least, her memory. The last thing she remembers is witnessing the murder of her next door neighbor by a dark stranger covered in frost. But it's the middle of June and the police aren't ruling his death a homicide.
Suddenly plagued with gaps in her memory and drawn to the sites of multiple murders, Leighton finds herself desperate to reveal the mystery of her past and to prevent more deaths in the future. But Leighton is entranced by the killer; a dark, brooding boy who can stop clocks and claims he's helping his victims, not hurting them.
If Leighton doesn't find a way to stop the murders and piece her past back together, she may lose more than her sanity. She may lose her life.