The Case of the Scorpion’s Tail

Peter Lynch was the actual mastermind behind the entire scheme. He had orchestrated Kurt's fake death and planned to murder Lisa, Lara, Sharif, and Barnett to claim the one-million-dollar insurance payout while framing the supposedly dead Kurt. Cléo discovered the money sack in the cave during their vacation and Peter revealed his plan, asking her to escape with him.

Earlier, Peter had arranged for Barnett to attack Cléo and leave behind the scorpion cufflink to make authorities suspect Kurt.

Kurt faked his death in a plane explosion en route to Tokyo with Peter's help. Peter and Kurt staged the plane explosion to make it appear Kurt died, allowing them to collect the insurance payout. Peter then killed Kurt later in the scheme to keep him silent and frame him for the other murders.

Peter acquired a photograph of Kurt wearing a scorpion cufflink, which fueled the theory that Kurt had faked his death.

The scorpion cufflink was a planted clue Peter used to frame Kurt. Peter had Barnett attack Cléo and leave behind the scorpion cufflink to make authorities suspect Kurt. The police deduced Peter's scheme when they realized the cufflink was a counterfeit of Kurt's real cufflink, matching a mermaid brooch from Barnett's mistress.

Peter acquired a photograph showing Kurt wearing the original scorpion cufflink, establishing the connection.

Peter killed these people to claim the one-million-dollar insurance payout and cover his tracks. He needed Lisa dead to steal the money after she cashed the check. He had Sharif killed to silence him. He killed Lara because she knew too much. He killed Barnett because he was Peter's accomplice who could expose the scheme.

The scheme was revealed when Cléo discovered the money sack Peter had hidden in the cave.

The police deduced Peter's scheme from the evidence: they connected Barnett's mistress's mermaid brooch to the scorpion cufflink found at the crime scene. Both were revealed to be fakes of Kurt's genuine cufflink. This proved someone was framing Kurt, pointing to Peter as the true mastermind.

Stanley discovered the scorpion cufflink on the floor after Peter left Cléo's apartment.

Peter had plotted the deaths with Barnett, who was Lisa's lover. Barnett helped fake Kurt's death and served as Peter's inside man. Peter also had Barnett attack Cléo and leave behind the scorpion cufflink as part of the frame job. Peter eventually killed Barnett to silence him.

Lisa planned to catch a flight to Tokyo to rendezvous with Barnett.

The incriminating letter was something Philip was using to blackmail Lisa. It potentially revealed Lisa's involvement in or knowledge about Kurt's death. A man with a facial scar (Sharif) murdered Philip and stole the letter before Lisa could retrieve it, giving Lara leverage over Lisa.

Philip threatened to expose the letter unless Lisa paid him off.

Lara was Kurt's mistress and claimed Kurt intended to divorce Lisa, marry Lara, and make her the insurance beneficiary. Lara believed Lisa had planned Kurt's death and used the stolen letter to blackmail Lisa, demanding half the payout. Lara denied killing Lisa when confronted.

Lisa met with Lara and Sharif, who had murdered Philip and stolen the letter.

While Peter slept on the boat, Cléo investigated the cave and discovered the sack containing the one million dollars Peter had stolen from Lisa. This was where Peter had hidden the money after murdering Lisa and staging the scene to make it look like Kurt had done it.

Cléo had observed Peter scuba diving into the cave with a sack that appeared empty when he emerged.

Cléo rushed to the boat's radio to call for help and stabbed Peter's shoulder with a harpoon. She then fled ashore with Peter in pursuit. Peter attacked her, but police arrived and shot Peter dead before he could harm Cléo.

Peter asked Cléo to escape with him, not realizing she would try to stop him.