In September of 2013, fishermen discovered an unusual cache of what at first appeared to be adult sex toys abandoned below a bridge in a reservoir just south of Dublin, Ireland. Soon thereafter, human remains were found in the forest.

After the evidence gathered by detectives leads the authorities to determine the identity of the victim, and the cause of her death, the investigation turns to pursuing the person responsible for committing the devilish crime.

The investigation, covering three police stations, over 5,000 hours of CCTV, numerous digital devices, hundreds of lines of inquiry, and an online world involving domination, submission, and torture, eventually identifies the killer.