After relic sorting specialist Jiang Wanning finishes a commission, an old key unexpectedly appears out of nowhere in the empty room. The number 02-17 on the back of the key pulls out a room that has disappeared from the blueprint, and also makes the Zhang siblings suspect that their father is hiding a secret. As wristbands, old photos, and shipping records appear one after another, the truth overturns guesses time and again. Jiang Wanning traces the clues to the end, and finally discovers that what her father left behind is not property, but a kindness that has remained silent for many years.