Kogoro inspects the car. There are no signs of a struggle—no blood, no torn fabric. The keys are still in the ignition. In the back seat, they find a briefcase containing architectural blueprints and a lunchbox that has begun to spoil. However, something is missing: the silver locket. Yukie had specifically mentioned it, but it’s not in the car or on the ground around it.
She then went back to the car, smashed his watch to show 2:15 PM (the time she wanted to fake), took the locket as a trophy, and drove back to the city using a back road. Her alibi was airtight because she had carefully planned the timing—the drive from the mountain to her friend’s house and the supermarket was exactly 90 minutes, which she accounted for by leaving the shrine at 6:00 PM, not 7:30 PM. She had set Keisuke’s car clock forward by 5 hours earlier that morning, so he arrived at the shrine thinking it was 2:15 PM, but it was actually 7:15 PM.
They search the surrounding forest. About 200 meters from the car, hidden behind a thick bush, they discover a narrow, overgrown trail leading to an abandoned, decrepit shrine. Inside the shrine, they find more clues: a discarded, empty bottle of sleeping pills, a woman’s hairpin, and a man’s muddy shoe print. Detective Conan Episode 406
She arrived at the shrine before him (using a different route) and waited. When he arrived, groggy, she confronted him about the locket. In his drugged state, he confessed and begged for forgiveness. She then pushed him toward the cliff. He stumbled, fell, and hit his head on a rock, then rolled into the river.
Yukie is arrested. As she is led away, she looks at Ran and says, "Tell him... tell my husband... I’m sorry we couldn’t keep the promise of the locket." It’s unclear if she means the promise to forget the past or the promise of their marriage. Kogoro inspects the car
Kogoro, Ran, and Conan drive to the area where Keisuke’s car signal was last detected. It is a narrow, winding mountain road surrounded by dense forest. After searching for a while, they spot a dark blue sedan crashed into a ditch off the side of the road. The car is empty, but the doors are unlocked.
The main suspect becomes Yukie Sonoda herself. But she has a solid alibi: she was at a friend’s house for tea from 1:00 PM to 5:00 PM that day, and then at a supermarket (recorded by security cameras) from 6:00 PM to 7:30 PM. She couldn’t have driven to the mountain, killed him, and returned in that timeframe. In the back seat, they find a briefcase
However, the locket Keisuke always wore did not contain a picture of a childhood sweetheart—it contained a picture of , the girl he killed. He wore it as a constant reminder of his guilt, a promise to himself to never forget the life he took and to live honorably.
Suddenly, the doorbell rings. Ran rushes to answer, hoping for a client. A well-dressed, distressed woman in her late twenties stands at the door. She introduces herself as . She explains that her husband, Keisuke Sonoda , a successful architect, has been missing for three days. She has already contacted the police, but since there’s no evidence of a crime, they have only issued a missing person notice and are not actively investigating. Desperate, she has come to the famous "Sleeping Kogoro" for help.