Doctor Dee serves as a faculty member and researcher at Endor College, specializing in the fusion of magical arts and scientific inquiry, particularly chemistry. He conducts extensive experiments focused on magical transformations. He collaborates closely with Headmistress Madam Mumblechook, sharing her obsessive objective to harness the power of the rare fly-by-night flower for their research.

Their joint project centers on using the flower's properties to transform ordinary humans into witches or warlocks. This obsession originated years earlier when they first discovered the flower's potential through Charlotte, a former red-haired student whose abilities inspired their work. After a disastrous failed experiment involving Charlotte's classmate, their methods grew increasingly unethical.

Doctor Dee maintains a laboratory dedicated to transformation spells, conducting experiments on both animals and humans. Animals like Gib-cat are transfigured into fantastical creatures against their will. Human subjects, including the kidnapped boy Peter, face similar procedures. Peter becomes a test subject for an experimental warlock-creating ritual, highlighting Doctor Dee's disregard for consent and safety.

His methods involve confinement and coercion; he imprisons Mary and Peter upon their arrival at Endor and seizes the remaining fly-by-night bulbs from Mary. The transformation process requires complex apparatus, consumes significant magical energy, and often yields unstable results.

The culmination occurs during the forced transformation of Peter, which fails catastrophically. The unstable magical energy traps Peter within a gelatinous monster that rampages through the lab. During this chaos, Mary retrieves a spell book containing counterspells. Peter utilizes one such spell to reverse the transformation magic, dismantling Doctor Dee's research, destroying the laboratory, and neutralizing the threat.