On his way home from work, Bill finds five charred bodies atop a bonfire on the roadside, close to a local farm. Pathology reveals that all five victims had been shot through the head with a nail, although this was not the cause of death. Raking through cases with a similar MO, Bill uncovers a series of murders committed by Frank McGill (Patrick Bergin), a former hitman who has been in witness protection since 1997, having turned Queen's evidence on his former gangland boss. (thetvdb.com)