12 Again — Sue Corbett

PATRICK MUST RACE AGAINST TIME TO FIND HIS MOTHER!
When Patrick's mother disappears right before her fortieth birthday, he has no way of knowing that she has magically turned twelve again. His family fears the worst, but Patrick refuses to give up hope. Unless he can get her back, he faces a life of waiting on his brothers. Then he receives an untraceable e-mail that adds to the mystery's already-puzzling elements -- a black rabbit, a hidden key, an amber-colored elixir, a new girl at school, and a full moon on Halloween night. Can Patrick do the impossible? Can he rescue his mother... and return his family's life to normal?