Hassan was left behind.
The man who had waited 34 years to be the king of Jordan was stunned. For weeks, he had heard the rumours that his days as crown prince were numbered; a Lebanese newspaper suggested that King Hussein believed that his younger brother was plotting a coup.
But the king had reassured Hassan only days earlier that he intended to make him regent. Hassan's desperate, melodramatic attempt to prove his good faith is already the talk of Amman.
He presented himself before the king and - according to impeccable sources - asked Hussein bluntly: "How have I offended you? Here is my gun. If I have been disloyal to you, please shoot me - but do not disgrace me."
The king ordered Hassan to take his gun back and reassured him yet again.
When a similar account to this story appeared in the small Jordanian newspaper Al-Majed, its editor was accused of "insulting the monarch".
Jordan's authorities are sensitive to the slightest criticism of the royal family, but in the days that have followed the king's death it has been possible to put together an account of Crown Prince Hassan's fall from grace.
In fact, the sequel to his astonishing gesture with the gun was, if anything, even more striking. The king called Hassan to the royal palace late on 20 January to present him with his letter of dismissal. A photographer was waiting to snap Hassan handing over his insignia to the new crown prince - and now king - Abdullah. Hassan returned to his car without the time to read the document; driving away, he turned on the radio only to hear the contents of the unopened letter on the national news.
Many Jordanians feel that the manner of his dismissal was unnecessarily cruel.
As Crown Prince, Hassan had been ordered by the king to handle Jordan's development projects - a role that inevitably brought him into conflict with the government of the former prime minister Abdul Karim Kabariti, who is said to dislike Hassan personally. Premiers believed that Hassan trespassed on their prerogatives - something he had no right to do since the right of succession is the crown prince's only constitutional power.
Even before King Hussein's brave, hopeless insistence of his recovery on 19 January, the royal court had been awash with stories that the monarch was turning against his brother. First, the name of Abdullah would be mooted, then that of Hamzeh, his son by Queen Noor.
Hassan's concerns only increased when he realised the extent to which his communications were being monitored - for years, he had spoken, half- jokingly, to visitors about the taps on his telephone.
In the Mayo Clinic in Minnesota, King Hussein was told that Hassan had tried to fire the chief of staff of the army, that Hassan's Pakistani- born wife, Princess Sarvath, had gone so far as to change the carpets in the royal palace in anticipation of becoming queen.
The truth appears to be more prosaic.
At a cost of more than pounds 3m, King Hussein had built a house for Field Marshal Abdul-Hafez Mureii-Kaabneh, a very ugly but otherwise magnificent pile on top of a hill outside of Amman.
Rumour had it that Walid bin Talal, a Saudi millionaire, wanted to purchase the property for pounds 10m but Crown Prince Hassan, after consultations with the king, told the Saudi that the property belonged to the field marshal. Hassan's response - which appears to have been in accordance with the king's wishes - nevertheless provoked the story that he wanted to remove the field marshal. And the king was not amused.
Then came the tale of the carpets. Hassan's home is a charming building once owned by the former British ambassador, Sir Alec Kirkbride, but last year the Crown Prince decided that after years of neglect, the house should be refurbished, along with its adjoining offices. Princess Sarvath, so it is said, wanted to change the decoration in both house and the office. And a new story, as unfair as it appears to be untrue, went the rounds - that the princess was "changing the royal palace" even before the sick king had died.
But Hassan could make dangerous mistakes.
Against the advice of his friends, he commiserated before parliament with the suffering of Iraqi civilians under United Nations sanctions. The Iraqi government reacted angrily because it believed that Hassan had not given sufficient support to the regime, while the king reportedly complained that the crown prince had not been tough enough on the Iraqis.
Princess Sarvath was also widely believed to want to name her son, Rashid, as crown prince when Hassan became king - an idea that would inevitably anger Queen Noor. Those around the princess advised her to forget the notion but it seems that Hassan, too, continued to toy with the idea of naming his own son crown prince once he gained the throne.
In the first days of his own regency, Abdullah showed considerable generosity to his deposed uncle. He greeted him warmly and - when Hassan offered to hand over control of the six academic institutions that he ran - the new king insisted that Hassan should continue to administer the projects.
In a nation in which the monarchy is the one unifying bond, it is as well that the two men appear to get on well. More royal shenanigans, and Jordanians will be wondering what kind of royal family they have inherited.