The tables are turned as 16-year-old Judy goes back in time to live in 1946. As Judy struggles to make friends and adapt to teenage life in the past, her grandfather, Levi, isn't much help. As college-bound Levi focuses on his friends, family, and schoolwork, Judy falls into the role of his tag-along little sister in her frantic search for direction.

In Their Day is the dramatic and emotional final installment of the My Guardian Grandpa comic strip series.