Lin Shiyan, the owner of an old bookstore, holds an antique pocket watch capable of reversing time. Every time Su Wanyi dies unexpectedly, he turns back the clock and does everything in his power to save her. But with each rescue, he loses a piece of his own memories of her—gradually forgetting how they first met, the song she loved most, and even why he must save her today. The numbers on the wristband counting down his remaining time decrease day by day, yet he continues relentlessly toward the end of time. Only at the very last moment does he finally understand: what she wanted was never for him to remember her, but for him to live well.