1975 Flashback to Thaddeus Mobley meeting Howard Zimmerman, a producer, at the event where he won his award. Howard suggests turning his book into a movie.
Howard watches a screen test for an actress, Vivian Lord. Tad comes in and is enraptured with her and Howard introduces them. Tad has been working on the screenplay. Howard fields a call from Warren Beatty, who isn't able to be in the movie. Howard manipulates Tad into using his book advance to fund the movie, using the actress’ sex appeal. Tad repeatedly writes Howard checks and grows a mustache, staying in LA far longer than he expected. Vivian uses him to buy her drugs and gets him to try cocaine. They have sex back at his motel room.
As Tad types up his screenplay, we see the action in animation form. The astronaut died when he and his android crash land on the Planet Wyh. He tells the android to get word back that the mission wasn't all for nothing.
It's revealed that Gloria is reading the book while on a plane to Hollywood. A man sitting next to her, who tells her he has flown already six times this week, talks to her about the book and waxes philosophic about the meaning of life.
Gloria reviews Ennis’ file while she's in gridlocked traffic. She arrives at a motel in the middle of a Santa Claus conference and is robbed of her suitcase by a man wearing an elf costume while she's checking in. She's in Room 203, the same room Thaddeus was in back in the 70s. When the police arrive, she asks them to run information about her Ennis case for her. The cop is hesitant but agrees if the plate number she gave for her robber checks out.
Gloria finds a pair of shoes behind the curtain in her room, initially thinking it's a person. She also finds a strange box behind the shoes. Gloria calls Nathan to check in by calling Donny and having him drive up to stop Nathan’s school bus en route. Donny reports back that the new chief is upset that Gloria went on this trip without authorization, but Gloria doesn't care. She explains that she might have a lead on the actress Vivian Lord.
Gloria goes to eat at a diner and questions Vivian, who is now an older woman working as a waitress. Vivian explains that she was on drugs at the time and is 29 years sober. She doesn't remember whether she met Thaddeus. Gloria asks her to stop by the motel if she changes her mind or remembers anything of note.
Gloria gets back to her room and finds her suitcase there. It's empty, save a candy wrapper and a note from Officer Hunt asking to buy her a beer.
Gloria goes to meet with Hunt at a bar. Hunt tries to sell her on the concept of Facebook, which she's not interested in. Gloria only wants to talk about whether Hunt found anything on Thaddeus Mobley. He tells her he didn't and then awkwardly and brusquely hits on her.
When Hunt steps away to use the bathroom, Gloria encounters the man who was sitting next to her on the plane, who introduces himself as Paul Moran and asks her questions about her life. Hunt comes back and tries to shoo Paul away, asking Gloria if he's getting laid tonight. Gloria rebukes him.
When Gloria gets back to her motel room, she finds a note from the new chief telling her to get her ass back home.
Gloria reads more of Planet Wyh and dreams of the story in animation. The story is about the android who continues to wander the earth for millennia searching for meaning, stopping every century to recharge.
The next day, Gloria visits the Writers Guild of America and asks the very disinterested woman working there if there's any information about Thaddeus Mobley. The woman brings her Thaddeus’ screenplay for his book (the script is spelled Planet Why). Gloria sees Howard Zimmerman as the producer and goes to visit a now very elderly Howard in the nursing home he lives in. She asks whether he knew Thaddeus.
At first, he pretends he doesn't and then tells her that Thaddeus was a failure and gives her a very nihilistic speech, kicking her out. A nurse tells Gloria that the only person who visited him was Gladys by she's long dead and that Howard has been there a long time, since an accident that they thought would leave him a vegetable.
Gloria continues reading Thaddeus’ story about the android, who only says “I can help” over and over again, existing on earth and witnessing civilizations rising and falling over many years. Eventually, the people he'd have gotten a message back to have all died out. Aliens land on earth and begin killing everyone, and the android is beamed up. Gloria gets a note from Vivian to give her a call when she wakes up.
Back in the 70s, Thaddeus is hopped up coke and goes to Vivian’s apartment to ask for more of it. Howard is there. The two reveal that they conned Thaddeus out of his money and that he won't be getting it back, with Vivian harshly telling Thaddeus that he got played. Howard chokes Thaddeus into submission. Thaddeus snaps and beats Howard viciously over the head with his cane, turning out Vivian afterward. But he stops before hitting Vivian and runs out.
In the present, Vivian tells Gloria this story at the diner, explaining that after that night she never saw Thaddeus again. Gloria realizes that that was Howard’s debilitating accident. She briefly wonders whether Howard might have sought revenge on Thaddeus, killing him many years later in Minnesota but realizes that it's logically unrelated. She leaves Vivian and goes to sit by the beach.
In the 70s, Thaddeus runs back to his motel room, quickly and paranoidly packing to skip town. He pukes into the toilet. In the present, Gloria packs to leave, spotting the toilet company, which is where Thaddeus got his fake name, Ennis Stussy.
Gloria flies back to Minnesota. The Planet Wyh ends with representatives from the United Congregation of Planets presenting the android with an award for his service. Having wandered the earth meaninglessly for 2.38 million years he collected invaluable data for them. They tell him he has helped and give him the go ahead to shut himself down. He does so.
Gloria goes to the Eden Valley funeral home and observes Ennis’ body with Nathan. They're the only mourners. Outside the funeral home, Donny finds Gloria and tells her that they found Maurice LeFay’s fingerprints at Ennis’ and that the gas station store witness ID’d him. He also tells her about the mysterious circumstances of Maurice's own death.
They agree to continue investigating after Arby’s, with Gloria having renewed hope in solving the case. The small box Gloria found in her room is revealed to have been taken back with her and in the trunk of her car.