Actor Mark Ruffalo is set to lead the Vatican thriller Santo Subito, helmed by Bertrand Bonello, who has previously made Saint Laurent and The Beast.

Set in the holiest city of Catholics worldwide, Ruffalo will play a morally complex investigator, Father Joseph Murolo, who is summoned to probe the life of Pope John Paul II in order to reaffirm that his path to sainthood is clean, after the seer's death in April 2, 2005. During the investigation, Murolo's faith is put to the test as he is drawn into a moral labyrinth.

The makers call the film a thriller with a theological reckoning where the protagonist's finding 'should not undermine' the sanctification of Karol Wojtyla, the first non-Italian pope in 450 years.

Scribe Thomas Bidegain, Oscar-nominated co-writer of Emilia Perez, joins the film.

Santo Subito is backed by the European production banner Vuelta, along with Mandarin & Compagnie, Indiana Production, and Madants.

The film is set to enter production in Italy and Poland on March 9 next year.