The flick sees the singer take on the role of gay policeman Tim Burgess and, according to reports, the One Direction star will shoot intimate scenes with co-star David Dawson - who has been cast as Harry's love interest, named Patrick, in the movie.
A source tells The Sun newspaper the "Watermelon Sugar" star is "really excited about the challenge," adding, "Harry will be having sex on screen and they want it to look as real as possible."
According to insiders, bosses plan to film two sex scenes between Harry and David and another where the hitmaker will be "naked on his own."
"Not much is going to be left to the imagination," they mused. "Harry is throwing himself into this new role and is really excited about the challenge, even though it's a daunting task."
"He always wants to do things that people wouldn't expect and challenge what people think about him - and this film will really do that."
"My Policeman" is the film adaptation of the novel of the same name by Bethan Roberts and also stars "The Crown" 's Emma Corrin. It tells the story of Tom, a closeted policeman who marries Corrin's Marion - despite his love for Patrick - due to social constraints at the time.
The movie is directed by Michael Grandage. Rumor has it, Linus Roache is tapped as the older Tom while Rupert Everett as Patrick and Gina McKee as Marion.