On His Watch

On leave from the FBI, Special Agent Jason Spark is enjoying some welcome peace and quiet when he’s called on to help the local sheriff’s department check out a 911 call. Expecting a prank or misdial, he unwittingly steps into a horrifying bloodbath straight out of a Hollywood slasher movie, complete with clues scrawled on the wall.

Nikki Hart’s husband and son are killed, but she survives, badly b...