Soul Traveler

No one knows exactly what a human soul is. Religious people claim it's a spiritual thing; others think it's simply the sum of one's thoughts, experiences, and memories. In this story, a deceased neuroscientist, Gregory "Dex" Poindexter, who has worked with trauma patients, has found a way to resurrect himself inside the brain of his ex-girlfriend, whom he had previously experimented on. The only hope of stopping Dex's plan to continue infecting others with his essence or soul resides with Samantha Mathis, an emotionally torn teenager, and her boyish math professor friend, Jeremy Williams. The two suspect that Dex has released a secret power that can destroy far more than one small Mississippi town. The confirmation of their discovery comes from a clue the "possessed" ex-girlfriend shouts the title of an old Supremes song, whose lyrics Jeremy can't get out of his mind, "You possess my soul now, honey..." When Samantha tosses in other clues they enter into a race to stop the resurrected Dex.