When a car is pulled from the sea in Northern Ireland, Detective Tom Brannick finds an ominous postcard connecting to a case from the past: an assassin nicknamed Goliath.

Tom reels from the discovery of three bodies buried 20 years ago-one of which may be his wife. Tom and Niamh interview the kidnap victim, but he won’t ID his abductor.

As Tom scrambles to cover up what he’s done, Adam Corrie is deemed a missing person and his house becomes a crime scene.

Tom’s superior is arrested and interviewed, but Tori worries there’s not enough evidence for a conviction. Niamh remains unconvinced that they’ve finally caught Goliath.