The death 40 years ago of Pope John Paul I, who reigned for just 33 days in 1978, paved the way for the Roman Catholic Church to have three pontiffs in three months.
And his death was followed by the election of the first non-Italian pope in 400 years, John Paul II.
- The 'smiling pope' -
On August 6, 1978, Pope Paul VI dies aged 80 of a heart attack after 15 years at the Vatican.
On August 26, Cardinal Albino Luciani -- the patriarch of Venice -- is elected pope under the name John Paul I.
Aged 65, the son of a bricklayer from northern Italy has "two deep creases which go right down to his chin, features which tell of his peasant origin: Venetian mountain people, simple, honest and hospitable," AFP reports at the time.
He demonstrates a more direct leadership style than his predecessors and avoids ceremony wherever possible.
Highly sensitive to poverty, the man known as the "smiling pope" for his warm and pastoral demeanour, calls for a fair wage for all.
But on the night of September 28-29, he suddenly dies, apparently of a heart attack, just 33 days after his election.
He becomes one of the shortest-lived popes in history.
The next morning, Vatican workers gather around little portable radios under the porch to discreetly listen to the news, AFP reports.
"To pilgrims who enter the basilica, they have to answer the question 'is it really true that the pope has died?' They reply 'yes' nodding their heads solemnly."
- Poisoned? -
The Vatican refuses to perform an autopsy, with speculation stirred by discrepancies between the official story of the discovery of his body and the facts.
"The pope was found on Friday morning with a serene face, whereas, according to a reliable Vatican source, the reported myocardial infarction should have affected his limbs or his facial features," AFP wrote.
Providence, negligence -- intentional or not -- of his own health, or a conspiracy: numerous theories will question the official account.
In 1984, British author David Yallop, who writes mostly about unsolved crimes, publishes "In God's Name" which suggests John Paul I was poisoned because he was determined to oppose the domination of the Vatican by the notorious P-2 masonic lodge.
The Holy See dismisses the theory as "completely absurd". The book is published in 30 countries and is translated into nine languages.
According to other conspiracy theories, the pope wanted to address alleged corruption at the Vatican Bank, notably involving its president, Monsignor Paul Marcinkus, who was suspected of links to the mafia.
A 2017 book by Italian journalist Stefania Falasca, however, refutes the criminal hypotheses.
She says he was found in the early morning by a nun who said he was sitting on his bed wearing reading glasses with several typewritten sheets in his hands.
The Vatican baulked at the idea of telling the world a woman had been in his bedroom and seen the body, so it changed the story, Falasca claims.
- First non-Italian pope -
Rocked by the death of two popes in the space of two months, the Church has to find a successor.
"It was already difficult to find a successor to Paul VI. How will the cardinals find such a good, such a cordial pope as Pope Luciani?" one retired woman tells AFP.
On October 16, after eight rounds of voting, white smoke finally emerges from the Sistine Chapel, the signal from the 111 cardinals that a new pope has been elected.
The massive crowd waiting in St Peter's Square celebrates joyfully.
"Non-Italian pope elected" AFP flashes, even before giving the name.
Against all expectations, the 58-year-old Polish Archbishop of Krakow, Karol Wojtyla, is chosen by the conclave.
It is a small revolution for the Church, which has not had a non-Italian pope in more than 400 years.
Wojtyla adopts the name of John Paul II in homage to his predecessor. He is enthroned on October 22, 1978 at the height of the Cold War.
Charismatic, a stickler for tradition, a doctrinal conservative while embracing modern ways of spreading the Gospel, he is credited with helping to bring down communism in eastern Europe while fighting against unbridled capitalism.
Although he does not succeed in fulfilling all his commitments, he is idolised by many worshippers as "God's athlete" for his physical presence.
He dies in 2005 after suffering for years from Parkinson's disease and is made a saint in 2014.