As the Catholic Church prepares to beatify Mother Teresa on Sunday, a new film on her life is being shot in Sri Lanka.
British actress Olivia Hussey wants a film the nuns will approve of
The Italian production, which will be shown in two parts, begins in Calcutta in the 1950s, with Mother Teresa still teaching.
It shows how the meeting with a poor dying man caused her to change her life and eventually found the Order of the Sisters of Charity.
Mother Teresa is being played by the 52-year-old actress Olivia Hussey, who says she always dreamed of this role.
"When I heard they were making a production I went down on my knees and I prayed; it sounds corny but it's the truth," she says.
Four days later, the script to Mother Teresa arrived with an offer.
Ms Hussey says her ambition is to make a film the nuns who knew Mother Teresa would approve of.
The producers thought Sri Lanka would offer good filming conditions
She says a previous film prompted them to walk out in protest just five minutes into the screening.
She has to play Mother Teresa from her 30s to her 70s - aided by a false nose and aged by plenty of eye make-up.
"They thought maybe I was a little too attractive to play it," Ms Hussey explains, adding "though I happen to think she was incredibly beautiful because beauty comes from within".
On set in Sri Lanka, there is a plethora of languages - English, Sinhala, Italian - as the crew struggles to prepare for the next shot.
Many of the scenes are filmed in a purpose-built "City of God" - the community established by Mother Teresa in Calcutta.
It has been constructed in a real slum on the edges of a rubbish dump - the acrid stench of burning plastic adding authenticity.
For one scene, Fort Railway Station in Colombo was emptied of commuters on a quiet Sunday to be transformed into Calcutta half a century ago.
The producers decided to film in Colombo rather than Calcutta because they said the crowds were more controllable.
"I always consider Sri Lanka a kind of diluted India," says Chandan Ratnam, head of Film Location Services, which managed the local end of the production.
Colombo's Fort Railway Station doubles as Calcutta
Mother Teresa is the first big international film to be shot in Sri Lanka for many years.
Attracted by last year's civil war ceasefire, the producers felt the security situation had improved.
Mr Ratnam says he has had several inquiries from film companies wary of other Asian locations.
Sri Lanka now hopes to promote itself as an ideal island location - with beaches, jungles and mountains all within easy reach.
The benefits are huge; international films can promote tourism, create hundreds of jobs and help train the local film industry.
Twenty years of civil war kept Sri Lanka off the movie screens and it is hoping to capitalise on that now.