A university reunion party that DI Richard Poole is attending is brought to an abrupt halt when one of the group is murdered with an ice pick in a closed circle group of suspects.
Tropes:
- Apologetic Attacker: Sasha, after stabbing the Victim of the Week with an icepick: "Sorry about that."
- Back for the Dead: Poole appears in the Cold Open of the Season Three premiere just in time to become the Victim of the Week.
- Call-Back: In "Death at the Clinic", an identity theft ring was uncovered in a private hospital. In this episode one of the suspects mentions the same clinic in passing and later it turns out that the murderer stole someone's identity.
- Cover Identity Anomaly: The murderer has assumed the identity of their sibling. However, Poole gives them a book which they say they have never read; but it's the novel on which their sibling did their dissertation at Cambridge.
- Dead Person Impersonation: "Sasha" is actually Sasha's sister, Helen Reed. Both of them were involved in the same auto accident, but only one survived. The authorities had no reason to doubt "Sasha" when she told them the deceased sister was Helen.
- Due to the Dead: After the case is solved, the team raise a glass to the victim.
- Fox-Chicken-Grain Puzzle: DI Goodman's chosen metaphor for how the murder was committed. Fidel still hasn't worked it out by the time the case is solved.
- He Knows Too Much: Poole had to die because he realized that one of the members of the university reunion group was an imposter. Dwayne points out the crucial clue that it only made sense for the murderer to have killed him at the villa, in potential view of witnesses, because there was a risk of imminent exposure, and they couldn't wait to commit the murder until Poole was alone.
- Revenge From Beyond The Grave: As Goodman notes, Poole didn't just discover something that led to his death, he left behind clues that "solved his own murder."
- Shout-Out: The murder of Poole in this episode bears a strong resemblance to Hercule Poirot's description of what he would consider to be the most interesting hypothetical murder to solve at the start of The ABC Murders and later used as the premise for Cards on the Table. The only difference is that the setup to the crime involves a game of charades rather than a game of bridge.
- Thanatos Gambit: Realizing that the woman claiming to be his best friend from college is really her supposedly dead sibling, Poole leaves (and even gets some mailed to the island from England) enough clues to expose the killer.
- Unwitting Instigator of Doom: After the case is solved, Poole's classmate and friend, who organized the reunion, laments that if she hadn't brought Poole and Sasha into contact with each other, Poole would still be alive.
