It stars Gregory Peck, Thomas Mitchell, and Vincent Price, and tells the story of the trials and tribulations of a Roman Catholic priest who goes to China to evangelise.

Father Francis Chisholm is visited in his old age by Monsignor Sleeth at his fictional Scottish parish of Tynecastle in Tweedside.

He learns that, after he left for the seminary, Nora had a child out of wedlock with another man, he goes to see her but arrives just as she dies, giving birth to a daughter, Judy.

Francis receives a shipment of medical supplies from his childhood friend, Dr William (Willie) Tulloch.

The Reverend Mother, a cold, aloof woman born in wealthy nobility, immediately causes friction between herself and Francis.

The mission is destroyed along with much of the town in a series of fires caused by imperial troops battling republican forces.

Afterwards Reverend Mother Maria Veronica apologises for her longstanding disdainful attitude to Francis, and realises he has a truly humble Christian spirit.

Actors considered for the role of Father Chisholm included Spencer Tracy, Orson Welles, Edward G. Robinson, Gene Kelly, and Henry Fonda.

Ingrid Bergman was considered for the part of Mother Maria-Veronica, though Rose Stradner, the wife of producer Joseph L. Mankiewicz, was cast instead.

Variety called The Keys of the Kingdom a "cavalcade of a priest's life, played excellently by Gregory Peck.

In a 2010 review, film critic Jay Carr wrote:Again and again, one is impressed by the depth of talent on studio rosters of the time, in this case 20th Century-Fox.

Not just Gwenn, Mitchell, Hardwicke, and Price, but James Gleason, Roddy McDowall (Chisholm as a boy), Peggy Ann Garner, Anne Revere and Benson Fong dot the cast list in this solidly crafted film – measured, stately, patient, never loud or pounding (except when the mission is caught in a war between imperial and nascent republican troops, and Father Chisholm briefly takes up arms!).

[6]The film was nominated for Academy Awards in the following categories:[7] Alfred Newman incorporated Irish and Chinese elements into the score.

The theme at the heart of the track, "The Hill of the Brilliant Green Jade", is associated with a Chinese nobleman (Mr. Chia) who befriends Father Chisholm after the latter has saved his son's life.