The Wasp Trap (2025) is a psychological thriller by British author Mark Edwards. Edwards is a bestselling author of more than 20 books, including the popular Magpies series and has sold over five million copies of his books worldwide. The Wasp Trap follows a group of former colleagues who reunite for a dinner party 25 years later. The reunion becomes a deadly game when armed captors take the group hostage, demanding the revelation of a dark secret from their shared past. The narrative alternates between the present-day home invasion and flashbacks to the summer of 1999. This historical setting was inspired by the author’s own experience working for a tech startup in a country house at the turn of the millennium. The novel explores themes including Betrayal Of Others in Service of Self-Interest, The Corrosive Power of Shared Secrets and Buried Guilt, and Technology and Innovation Breeding a False Sense of Control.

This guide refers to the 2025 Atria Books hardcover edition.

Content Warning: The source material and study guide feature depictions of graphic violence, death, sexual content, cursing, substance use, emotional abuse, sexual assault, and physical abuse.

Plot Summary

In July 1999, Professor Sebastian Marlowe hires six young individuals to work with him on developing an innovative dating website, eventually named the Butterfly Net. The six individuals who come together at Thornwood (Marlowe’s estate in the English countryside) are Lily, Sophie, Georgina, Rohan, Theo, and Will. Professor Marlowe acts as an enigmatic mentor to them; the six team members are aware that he is an expert in psychology, who became interested in studying psychopaths after his wife, Barbara, was murdered by a serial killer. During their time at Thornwood, the team members also encounter Dominic (Professor Marlowe’s nephew), Eve (who works as household staff), and James (the project’s angel investor).

In an intense and high-pressure atmosphere, the team members develop an innovative online dating platform that uses psychological assessments to determine potential compatibility between matches. Lily also becomes interested in using similar psychological assessments to determine if an individual can be categorized as a psychopath. She works on a secret side project to develop this assessment (known as the Wasp Trap). To the surprise and frustration of the group, on the night before the Butterfly Net is supposed to launch, Professor Marlowe shuts down the project and sends them all home with no explanation. A week later, Marlowe informs them that Dominic has drowned in the lake on the estate.

Time passes, and the team members lose touch with one another. Theo and Georgina (who began a relationship during the summer of 1999) get married and have two daughters, Olivia and Mia; Theo’s successful career allows the family to live in the posh London neighborhood of Notting Hill. Early in 2024, Professor Marlowe dies; shortly thereafter, Theo and Georgina invite all of the team members to a dinner party at their home. Will is excited about the dinner, because it will give him a chance to reconnect with Sophie: He was in love with her during the summer of 1999 but never confessed his feelings.

In February 2024, the guests assemble at Theo and Georgina’s mysterious home. The house is equipped with many high-tech security features but these features repeatedly malfunction, making it hard for the guests to leave the house or contact the outside world. The house also may have a hidden secret passage. The six original team members are joined by a mysterious man named Finn, who claims to have been Professor Marlowe’s assistant during his final years. Will is suspicious of Finn. A chef named Callum and his assistant, Amber, are also present, as they have been hired to prepare and serve the food for the evening.

Early in the evening, Georgina and Theo explain that their eldest daughter, Olivia, has been missing for almost a year. Their other daughter, Mia, still lives with them but they explain that she is staying at a friend’s house. Unbeknownst to anyone in the house, Mia is actually hiding upstairs. The atmosphere grows more tense and sinister as the guests hear strange noises, lose access to Wi-Fi and cell signals, and become unable to leave the house as the security system malfunctions and traps them inside. Suddenly, Callum and Amber take the group hostage, wielding guns. Callum and Amber explain their goal is to force one of the guests to reveal a secret from the summer of 1999. They do not know what the secret is or which of the guests is concealing it but claim they will recognize it when it is revealed.

Theo is the first character who is forced to confess a secret, and he admits to engaging in blackmail, but Callum declares this is not the secret he is looking for and kills Theo. Will learns Finn is a private detective (not Marlowe’s assistant), but Callum kills Finn before he can reveal anything else. Next, Will confesses that he and Georgina slept together during the summer of 1999 (even though he was in love with Sophie). Callum is also unsatisfied with this secret, but it leads Sophie to reveal that she shared Will’s feelings. Lily confesses to a more dramatic secret: When Lily was developing her assessment to measure the odds of an individual being a psychopath, Dominic scored extremely high.

On the night before the launch of the online dating platform, Lily witnessed Dominic kill Eve (the young woman who worked in the house) and Lily drowned Dominic in the lake. She justifies this choice because she believes his psychopathy score makes him dangerous. Lily returned to the house and told Professor Marlowe what happened (including Dominic’s score). Marlowe agreed to keep the secret: He sent the team members home, shut down the dating app project, and presented Dominic’s death as accidental. Callum declares this is still not the secret and shocks the group by bringing a new person into the room: Dominic.

Dominic explains that when Lily fled the scene, he was not dead. Professor Marlowe helped him cover up Eve’s death (they hid her body in the lake) but then forced Dominic to participate in research into psychopathy in exchange for Marlowe protecting his secret (and eventually allowing Dominic to inherit his fortune). When Marlowe became ill, Dominic began to feel hopeful about his future, compounded by having begun a relationship with Amber. Just before Professor Marlowe died, he confided to Dominic that someone possessed a secret that could prevent Dominic from inheriting the estate. Dominic knew this person had to be one of the six team members, but he didn’t know which one. Dominic, Callum, and Amber are working together to uncover the secret and are prepared to kill the team members if they don’t comply.

Meanwhile, while these events are unfolding downstairs, Mia has been hiding upstairs and trying to find a way to escape. When Olivia vanished, Mia couldn’t accept that her sister would run away and hired Finn to work on the case. Eventually, Mia and Finn concluded that Olivia’s disappearance might be connected to Thornwood and one of the team members; they told Georgina about their investigation and proposed a dinner party that would bring the team members together and give Finn a chance to observe them. The plot by Amber, Callum, and Dominic has thrown this plan into chaos and as Mia becomes more desperate to escape, she happens upon the secret passage (which Mia suspects that Olivia might also have found before she vanished).

While Mia tries to use the passage to escape, Georgina accidentally reveals that she witnessed Dominic and Professor Marlowe hiding Eve’s body after the murder. She blackmailed Marlowe with this information and on his deathbed, Marlowe passed the information along to Dominic (revealing that someone knew about his crime, but not who it was). Inflamed by jealousy and Dominic having lied to him about the secret, Callum and Dominic begin fighting. In the ensuing chaos, Georgina manages to kill both Callum and Amber. The team members flee to the cellar but Dominic shoots and seriously injures Sophie. Will knocks Dominic unconscious but the team members are still unable to get out of the house or call for help.

Mia emerges from the secret passage into the cellar, surprising Georgina and the other team members. Guided by information she learned from Olivia prior to the latter’s disappearance and the contents of a text message downloaded from Olivia’s phone, Mia found a secret trunk hidden in the passage. Inside the trunk are a number of items but most importantly, Olivia’s diary. Mia reads her sister’s diary which confirms that Olivia also stumbled upon the secret passage and the same trunk. In the trunk, Olivia found Georgina’s journals, which detailed Georgina blackmailing Professor Marlowe and the fact that Georgina had switched her high-scoring psychopath test results with Dominic’s. When Olivia confronted her mother, Georgina killed her. Mia now confronts her mother with evidence of her various crimes.

Georgina admits to being a psychopath who killed her own daughter. She announces her plan to kill all the remaining team members in order to protect her secrets and urges Mia to help her. However, Mia ends up striking her mother in the head, knocking her unconscious. Mia also has a key that opens the one door that is not controlled by the security system, so with Georgina and Dominic immobilized, Will is able to get outside and summon help. Sophie is taken to hospital and Georgina and Dominic are both arrested.

In the aftermath, the surviving team members plan to move forward with their lives and Sophie and Will happily begin a romantic relationship. Mia goes to live with her paternal grandparents, but she secretly obtains a copy of the psychopathy assessment that Lily developed in 1999 (Georgina had stolen a copy of the assessment saved to disk and kept it in the trunk). The novel ends with Mia preparing to take the assessment and determine if she is a psychopath.