Dead Alley - S. A. Larsen - Bog

Sixth-graders Ebony Charmed and Will Fleishman are up to their graves with spirit training. That's their reward for saving Motley Junior High from a fiery serpent. More homework.
But that didn't stop them from secretly casting spells to find the dark elf that stole their friend Lance's body. They certainly couldn't leave it to Motley authorities. The last time Ebony left things to adults, her mother lied to her and a fire giant kidnapped her father (which she still believes is her fault).
When undead crows invade the boneyard and strange flower petals infect the ghost residents, they realize they are in over their heads. Clues point to Dead Alley - the forbidden section of the boneyard - where the dead have begun to be not so dead. When Lance's spirit goes full-on berserker, the duo must find a cure. Before the infected ghosts turn zombie and Lance remains trapped there forever.