Frannie in Pieces: Save the Blues for Last by Delia Ephron
After Frannie's artist father dies, she finds a handmade jigsaw puzzle in his studio that she assumes was a birthday present (early for once) for her. She keeps the puzzle a secret from her mom and stepdad and works it late at night, when things start to get weird and she finds herself in the puzzle. By day she's stuck working at a summer day camp, a job that her mom has foisted upon her, and making up with her best friend, with whom she's estranged basically for just having a boyfriend.
I won't give any spoilers as to what Frannie finds in the puzzle and how it (of course) helps her deal with her father's death and reconcile with her mother. But I will say that I just didn't buy the magical realism. This book should have either just dealt with a girl dealing with her father's death, or it should have gone all the way into the mystical instead of leaving us trudging through chapters about the annoying fellow counselors at the camp. NAY.