The Last Rung on the Ladder is a short story by Stephen King, first published in King's 1978 collection Night Shift.
Synopsis[]
The protagonist (Larry) is burdened with deep guilt and regret after discovering that his estranged sister has committed suicide. He recounts one fateful day long ago when the two were children, playing in their family's barn. They had a game where they would take turns climbing to the top of a very tall ladder in their barn, and leap off into a huge haystack.
On one of his sister's turns, the rickety old ladder broke, leaving her dangling desperately to the ladder's last rung. He desperately piled hay below her, and when she couldn't hang on any longer he told her to let go and she did. The hay broke her fall and saved her life, but he was astonished when she told him that she hadn't looked down before letting go, and didn't know about the hay. She simply trusted him to save her.
He tells of how the intervening years were not kind to her, and how he was too wrapped up in his own affairs to come to her when she needed him. The story ends as he reads the final letter she had written to him a couple weeks before she jumped off a building to her death; one that would have made him realize how desperately she needed him to save her again.