Acclaimed filmmaker Deepa Mehta is developing “Sher,” a comedic take on the Sherlock Holmes universe that reimagines the detective’s legacy through an unexpected Indian connection.

“It’s a complete fun take on Watson,” Mehta tells Variety. “Sherlock Holmes is dead, and Watson is trying to sell his book about him everywhere, desperate. He’s not doing too well, and he comes to Calcutta.”

The film follows Dr. Watson as he gives a poorly-attended lecture in Calcutta (as Kolkata was known then) before making a startling discovery — Sherlock Holmes has an illegitimate daughter named Sher living in the city, born from an affair with “an Indian young woman while he was in Cambridge.”

The script, by British writer Johnny Gurzman, represents a commercial departure for Mehta, known for her more dramatic works including “Fire,” the Oscar-nominated “Water” and “Funny Boy.” “It’s great fun. It’s really interesting. Probably one...