Not the worst friend in the world

Eleven-year-old Lou wishes she could turn back time to mend her friendship with Francie after a terrible fight, so when Lou befriends Cece she is eager to prove herself, but as she uncovers the truth about Cece's family, she grapples with what being a good friend means.
"It's the thirty-fourth day of sixth grade at Our Lady of Perpetual Help in Mayfield, Missouri, and eleven-year-old Lou wishes she could rewind time. She wants to go back to the ninth day of sixth grade--the day before she fought with her best friend, Francie, and said the terrible, horrible things she can't unsay. Then the new girl, Cece Clark-Duncan, passes Lou a mysterious note. It says she was kidnapped. (!) If Lou can help Cece, maybe she can prove she's not the world's worst friend. Maybe she can even win back Francie. But if Lou can't help Cece, the stakes might be higher than friendship." -- Jacket.