Stilwell compiles all the reports on the missing hikers into a three-ring binder, his own “murder book.” Using Bosch’s method, he lets it fall open at random. The binder opens to crime-scene photos from the excavation of Neary’s body, which was buried near a live oak tree in Griffith Park. Stilwell notes that both victims were buried at the bases of trees.

After texting Ballard to request a copy of Metier’s autopsy report, he studies interview summaries with Neary’s family and friends, a topographic map of the park, and a collection of photos and news videos taken during the massive public search for Neary after she was reported missing.

While watching a KCAL 9 News video from the search for Neary, Stilwell notices a live oak tree in the background with a distinctive, lightning-split trunk. He recognizes it as the same tree where Neary’s remains were later discovered. In the news clip, a park ranger is being interviewed in front of that very tree. When the ranger turns his head, Stilwell freezes the image and is stunned to recognize him as Kent Middleton, the Catalina Island Conservancy (CIC) ranger he met at the Metier crime scene.

Stilwell calls Ballard and explains his theory that Middleton killed Neary and buried her under a memorable landmark so that he could easily return to the grave. When her bones were discovered and removed years later, he lost his trophy site. Stilwell posits that Middleton then secured a transfer to Catalina so that he would have access to Metier’s burial site in the ironwood grove. He also suggests that Middleton intentionally unearthed Neary’s remains himself, which would fit the pattern of the deliberately planted backpack. Ballard agrees with the theory and asks Stilwell to casually question Middleton.

Stilwell checks which rangers are on duty and finds them at the Avalon Beverage Company (ABC) vineyard investigating an act of vandalism. ABC recently acquired the rights to expand the vineyard, using up a lot of Catalina’s limited water supply and leading to protests and vandalism. The owner, Oliver Marquez, is irate that someone destroyed three rows of his young grapevines, which will take years to replace.

During his investigation, Stilwell discovers a four-foot cut in the chain-link fence that separates the vineyard from the adjacent CIC land. He follows a path into the protected chaparral and arrives at a clearing known as the San Pedro picnic grounds, finding no clear evidence of the vandal’s trail. However, on his way back to the fence, he spots a CIC wildlife camera mounted on a post in the brush, which may have captured the perpetrator.

Stilwell goes to the Hotel Atwater to interview Helena Novak, the viticulturist who found the damaged vines. Novak explains that the cuts are so severe that the vines will likely die. She reveals that the vineyard has been struggling with other problems, including a fungus called black rot and a significant labor shortage caused by recent ICE activity on the mainland. The previous year, Marquez had to hire local high-school students, including his own grandson, to help with the harvest. Novak adds that the destroyed vines were French clones, a particularly expensive variety to cultivate.

The next morning, Stilwell calls Mick Dunaway, the captain of the CIC rangers, to arrange a meeting with Kent Middleton and to ask about the wildlife camera footage. Dunaway has already reviewed the video and shows it to Stilwell. The camera captured a figure in a yellow-and-blue shirt one day before Stilwell investigated the site. In the footage, the person stumbles and yells in a voice that sounds young.

Dunaway informs Stilwell that Middleton is currently supervising a retreat for the local high school’s senior class at Eagle’s Nest. Dunaway agrees to call Middleton away from the event and have him meet Stilwell at the ranger headquarters.

Stilwell meets Middleton at the ranger barracks. Middleton gives him a thin file on the search for Angela Metier, which contains a list of citizen volunteers, including Tash. During their conversation, Middleton mentions that he lives with his girlfriend, Gwen, a bartender at The Buffalo Nickel, and that he has applied for a state park-ranger position, hoping for an assignment in Malibu, Florida.

Stilwell accepts a ride with Middleton up to Eagle’s Nest, taking the opportunity to observe the man. When they arrive at the high-school retreat, Stilwell sees students wearing their school colors: yellow and blue. He quickly spots Marquez’s grandson, who’s wearing shorts that reveal a large white bandage wrapped around his right calf.

Stilwell drives to the ABC vineyard and confronts Oliver Marquez. He informs Marquez that he’s not filing a crime report because he knows the vandalism was an insurance fraud scheme. Stilwell reveals that Marquez’s grandson admitted that he damaged the vines for Marquez. The bandage on the boy’s leg was from an injury he sustained after stumbling into a cactus while carrying out the act. Stilwell warns Marquez that if he proceeds with an insurance claim, he will arrest him for fraud. Marquez orders Stilwell off his property. Stilwell calls Tash, who confirms that Middleton lives with Gwen Bassett.

Stilwell confirms Bassett’s address at the Bird Park apartment complex. He recognizes that the complex’s isolated canyon location will make surveillance challenging. He calls Detective Ballard to update her on his conversation with Kent Middleton, including Middleton’s desire to transfer to Malibu, which is the location of another unsolved missing hiker case.

Ballard decides to immediately dispatch a surveillance team to Catalina. Stilwell calls the Bird Park manager, Lukas Hernandez, and secures a vacant two-bedroom townhouse. Stilwell tells Hernandez that the incoming tenants are police officers but doesn’t reveal details of the case. The unit is directly across from Middleton and Bassett’s apartment.

Stilwell goes to the ferry dock to meet Ballard, Laffont, and Paul Masser, a former prosecutor. He’s surprised to see Detective Simon and his partner, Detective Bob Trestle, disembarking. Simon claims that they’re going to take photos and measurements at the airstrip, which Stilwell assumes means that Deputy Ramirez has remembered the incident.

Stilwell arranges for Deputy Dawn Stabile to drive Simon and Trestle to the airport, secretly instructing her to watch them. Because a local paper recently published a photo of Ballard and Stilwell at the Metier crime scene, they decide that Laffont and Masser should go to the apartment alone to avoid being recognized. Stilwell tells them to claim that they’re potential buyers or insurance investigators looking into the recently vandalized ABC vineyard.

Before taking the ferry back to the mainland, Ballard tells Stilwell that they have hit a dead end with the Ford key found in the backpack since Neary’s Ford Mustang was salvaged years ago. She also voices her concern over the lack of hard evidence against Middleton and the high cost of a prolonged surveillance operation. They agree to maintain surveillance for a week before making any decisions.

Stilwell arranges for Simon, Trestle, and Ballard to leave on the same boat, using his connection with Kim Krabill, the ferry’s captain. Simon and Trestle refuse to tell Stilwell about their investigation, but as he boards, Simon gives Stilwell a private wink. Ballard reveals that she’s Hawaiian, and Stilwell notes that he spent time in Hawaii while serving in the Navy. He says “goodbye” to her in Hawaiian. Deputy Stabile reports back to Stilwell and says that she saw Simon and Trestle conducting a search in the brush about halfway down the airstrip, a different location from the initial crime scene, and also examining the surface of the tarmac.

Stilwell drives to the airstrip, and the manager, Rich Burkhardt, shows him cell-phone pictures he took of Simon and Trestle. The photos reveal that they were examining an ironwood tree on the slope next to the runway.

Stilwell goes to the tree and climbs it. About 12 feet up, he discovers a sniper’s nest. Small branches have been snapped to open a line of sight to the spot where the plane stopped the night of the shooting. On the ground 15 feet from the tree, he finds the discarded branches. Stilwell photographs the nest and the branches as evidence, confirming that the shooting was a planned assassination.

Back at the substation, Stilwell fields a report about graffiti reading “FSiD” on the island’s historic chimes tower. He then calls Detective Simon, who answers on a disposable phone.

Stilwell reveals his discovery of the sniper’s nest. Simon admits that Lieutenant Lambert claimed that Quigley requested the Catalina transfer. Lambert checked the names of all the confidential informants that Quigley had put in their encrypted system, but the informant who set up the airstrip operation wasn’t among them. Simon and Stilwell agree that Quigley’s uncleared informant must have set Quigley up to be assassinated, but they don’t know why. Stilwell realizes that Captain Corum is orchestrating a cover-up to protect the department from a scandal and that he’s being positioned to take the fall.