Dead Boy Walking:

When a local high school student is murdered, his friends rally together to find his killer, but they get help from an unexpected source - their dead friend - who is having issues himself as he struggles with existing between life and death, trying to figure the origin of a ring that has supernaturally attached itself to his finger and glows bright amber, and fighting an unseen adversary who wants to bring him back where he belongs - dead. All of these are intertwined with each other, he just doesn't know it.