When the "no-brained" Lu Tu (played by Peng Yuchang) meets the "unhappy" Ling Min (played by Li Gengxi), two young people with serious illnesses but very different personalities, because of the promise of "life relay", accidentally embark on a healing journey full of love and strength. The film is the final chapter of director Han Yan's "Life Trilogy", partly based on the documentary report "The Most Utilitarian Marriage Transaction, the Most Emotional Eternal Promise".