The Spirit Tree by Jacqueline Kirk
Approx. 27,440 words.
Published on May 10, 2011.
The Spirit Tree cleanses the souls of the newly dead but an evil soul has tainted it and its Guardians, twisting them into something evil.
When Michael's mother becomes a restless spirit, he and his friend James are determined to heal the Tree any way they can! With the help of Billy Blin, a Guardian who escaped the taint, they battle their way to the Tree even when the forest itself fights them!