At a picnic in the forties, a little girls disappears during an Easter Egg hunt (presumably it’s somewhere around Easter). Forty years later, the mother is dying and the little girl returns to visit her father and help his transition to life without his wife. Strangely, she hasn’t changed a bit, yet he accepts it as normal. When they go to see the mother, she is dead, and only then does he realize what is happening.
The wife says her goodbyes and the husband realizes that he’s on his own to carry on by himself, and one day he will be able to go with them. As the episode fades, we see a book on the nightstand that has been referenced throughout the episode. The mother and father have been writing it, apparently for forty years. The title is Without Diana.