In the gripping fourth episode, Pip begins to doubt the significance of her probe into Andie Bell's mysterious disappearance. Just as she fears her efforts have been futile, a monumental revelation shatters the veil of obscurity. The episode kicks off with Ravi and Pip unearthing a stash of drugs hidden in Andie's toy bunny, parked inconspicuously in a field. Amongst the contraband, they stumble upon a handwritten list of customers, scribbled on a scrap of paper in a cryptic code.
Pip rushes to school, having skipped three classes—a feat unprecedented in her record—and narrowly avoids missing her crucial Cambridge entrance interview. Though the interview proceeds smoothly, Pip's thoughts wander, unable to focus on impressing the interviewer.
Later, as she assists her friends in planning a reunion for the 2019 class, Pip scribbles aimlessly on the mysterious paper. Suddenly, she recognizes the embossed name of a local hotel at the top. She promptly calls Ravi and, against her mother's wishes, meets him to investigate if Andie ever frequented the hotel.
The hotel exudes an air of sophistication, but the receptionist is nothing but rude. Ravi, quick-thinking, pulls the fire alarm when no one is watching. As guests and staff evacuate, Pip sneaks behind the reception to swipe an outdated visitor book. The duo hide in a hotel room, amidst the chaos, and realize that the mosaic-tiled bathroom floor matches the backdrop of the photo of Andie in her underwear, which Max keeps in his bedroom—a definitive sign that Andie has indeed been there.
Later, they delved into the visitor's ledger and discovered that Andie and her elusive older companion had checked in under aliases. Pip's heart skipped a beat when she spotted her father's name, Victor, amidst the entries. The following morning, Pip grilled her mother about the time her father had traveled to Nigeria to visit their grandmother, querying why they hadn't all gone together. Her mother offered a feeble excuse of the flight being too long for two young children, but Pip sensed the lie beneath the words.
As Pip walked to school, Dan Da Silva intercepted her and tried to coax her into his police car. She remained steadfast until he revealed that he knew of her trespass into the Bell household. With no other option, she reluctantly accompanied him. They returned to the Bell residence, observing Jason Bell washing his car. Dan recounted his and his sister Nat's tumultuous upbringing, mentioning that Jason had been a guiding light for him, encouraging him to join the police force. He guilt-tripped Pip for prying into Andie's case, emphasizing that her parents were decent souls still reeling from the tragedy. Then, he showed her a video of Sal's police interrogation, revealing a volatile side of the young man as he flew into a rage when no one heeded his answers. Pip was startled by this new facet of Sal.
Back home, Pip confronted her mother about Victor's recurring visits to Nigeria, declaring that she knew he hadn't gone there since his name appeared in the hotel ledger. Her mother conceded that they had gone through a rough patch, and she had suspected Victor of infidelity, which was unfounded. Pip delivered a passionate speech about the unreliability of trust, convinced of Sal's guilt after witnessing his愤怒 outburst. She stormed off, leaving behind a trail of wounded emotions.
At their favorite lake, Pip encountered Ravi and poured out her heart, sharing the video and her flashbacks of revealing Andie's hiding place to Sal. Ravi was disheartened that he had trusted her, but now even she believed in Sal's guilt. He walked away, their friendship reduced to ruins.
Amidst her turmoil over Ravi and the mysteries surrounding her investigation, Pip rushes home, barely averting a collision. She eventually pulls off into a serene field, allowing her tears to flow freely. Once she regains her composure, she seeks refuge at Cara's. Her friend offers sage advice and, to distract her, they immerse themselves in preparing Naomi for the school reunion.
As Cara steps out to fetch a hair straightener, Naomi broaches the subject of the case, and Pip reveals her suspicion that Sal might be the culprit. A shadow crosses Naomi's face, and she urges Pip to inspect her laptop. She divulges the password and directs Pip to a secret Instagram account. Pip, sneaking into Naomi's room, is startled to discover a photograph of Max, Naomi, and their friend, captured on the night of Andie's alleged murder by Sal. The timestamp reads 12:06, a stark revelation that someone must have snapped the picture—indicating Sal didn't leave the party at 10:30, contrary to his friends' testimonies to the police.
Pip hurries to confront Naomi at the reunion, but Max and Andie's sister, Becca, catch them heading toward a classroom. Inside, Naomi struggles to confess the truth, but she acknowledges Pip's suspicion that they all lied to the police about Sal's departure time. When Pip inquiries about the reason for the deception, Naomi confesses, "We had to lie. They found out about what we did..." But what dark secret did Naomi and her friends conceal? And how does it intertwine with Andie's mysterious disappearance?
