Dmitri helped Vladimir steal "The Nameless Book" during a paranormal conference while the Ghostbusters performed a demonstration of their equipment.
They met up with the Old One Cult and began the process of awakening the Old One. However, the pedestal holding up the book kept sinking. Dmitri was forced use his back to properly prop it up.
After the Ghostbusters defeated the Old One, he and Vladimir were arrested.
Dmitru is Maximov's comic foil, as he often takes his abuse. He was somewhat upset when he found out that when the Old One promised his partner that he would rule the world, he would not rule alongside him.
The Real Ghostbusters