The instant New York Times bestseller - a fiendishly clever, nostalgic, and tender novel about cherishing what we have while there is still time

By her fortieth birthday, Alice Stern thought she's have figured it out, and have years left to spend with her father, Leonard. In reality, Alice is far from ready for the next big milestone, and Leonard is very sick.

When she wakes up outside their old apartment on her birthday, she's greeted by a much younger Leonard, clutching a sixteenth birthday card for Alice, who rather than fearing middle age, is hurtling towards adulthood. Soon, Alice discovers how she got back to 1996, and that she can keep on coming. But faced each time with different versions of her life, it's on her to not lose sight of the things she wants most . . .