WHAT has been happening on the sedate avenues of Beijing's diplomatic quarter since Wednesday is the stuff of spy novels.
A North Korean defector, Mr Hwang Jang Yop, has been in the South Korean embassy, to which he fled on Tuesday. Agents of the last Stalinist state of this century watch and wait in North Korean embassy cars outside, distinguishable by their grim faces and lapel badges of the late communist, leader, Kim Il sung.
Officials of the Chinese and South Korean governments come and go. Soldiers block off streets. Mysterious men photograph each other. Foreign correspondents lurk behind trees.
The dramatic flight of one of North Korea's inner elite has raised many questions. North Koreans say the 72 year old adviser to their current leader Mr Kim Jong Il, was kidnapped.
But the South Koreans have produced a photograph of a calm looking Mr Hwang allegedly writing a four page note inside their compound, in which he describes his personal torment at deserting a starving country which had lost its senses.
Meanwhile all over town diplomats buzz with excitement at the prospect of what Mr Hwang, the most senior Pyongyang official ever to turn traitor in 40 years, might reveal to the world.
Mr Hwang has been close to the leadership in Pyongyang since the Korean war. He was a major architect of North Korea's guiding philosophy of juche, or self reliance - akin to the old Sinn Fein idea of "ourselves alone", or Stalin's "communism in one country".
Educated in Moscow, he taught Marxism Leninism to Mr Kim Jong Il in college. A sage and scholarly man, according to those who have met him, he was highly respected by his peers in a country where Confucian regard for education blends with an orthodox Stalinism which envisages war as a legitimate tool to reunite the country. He was the party official who met foreign dignitaries in recent years as the personal representative of Mr Kim.
It was the prospect of reckless military adventures by the North Korean army which persuaded Mr Hwang to flee, according to his own note, which Pyongyang officials dismiss as the invention of Seoul's secret police.
His family would think him "crazy" for what he did, he admitted, but there were those in North Korea who would turn the south into a "sea of fire" while talking of reunification. "How could you regard this as the behaviour of sane people? Can we call people sane when they talk of having, built a utopia for the workers and farmers when the workers and farmers are starving?"
On the surface the request for asylum looks like the act of a disillusioned party man. Low level desertions both ways in Korea are not uncommon. But in the pantheon of deserters from communist countries, the party theoreticians have always been the least likely to jump ship.
Mr Hwang was also a family man with a wife and children, making his defection all the more puzzling, according to a source close to the North Korean government.
There are other intriguing questions. The North Korean politician was returning from a two week visit to Japan. Why did he not defect in Tokyo rather than the uncertain environment of China, North Korea's ideological ally? Perhaps his travelling companions watched him too closely in Japan, suspecting his intentions, and relaxed too much when they reached Beijing on a stopover on the way home. But then, why not the US embassy in Beijing?
What we are witnessing in the tree lined streets of Beijing's embassy district is most likely to be the fall out from a power struggle in which an increasingly pragmatic Mr Hwang was on the losing side, according to observers.
The internal strife probably pitched this professor of philosophy against the military chiefs as they pushed for supreme power for Mr Kim Jong Il. Mr Kim has been army commander in chief for many years but the two key posts of general secretary of the ruling Workers' Party and head of state had eluded him.
Those promoting Mr Kim inside North Korea as all powerful successor to his father Kim Il Sung have, however, managed to secure his appointment this coming July as general secretary, according to the source. This decision - not generally known in the West - may have triggered Mr Hwang's flight.
But whatever the reason for Mr Hwang's surprise taxi journey to the South Korean embassy in Beijing on Tuesday, the price of his sanctuary will be disclosure of some of the secrets of the most secretive country in the world.
Just why, for example, did Pyongyang despatch a submarine with 26 armed infiltrators on an ill fated trip to the south last September, at a time when it was seeking better relations with the West to secure food aid to avert famine? Who was behind that?
At the end of December North Korea gave in to US pressure to apologise for the incursion, which turned into a fiasco when the submarine foundered on rocks. It promised to "make efforts to ensure that such an incident will not recur". North Korea even undertook to join the south and the US in peace settlement talks 43 years after the end of the Korean War.
This rare apology was a recognition that having lost the economic and political support of Russia and China - and of wealthy north Koreans in Japan - and having been devastated by floods in two successive years, Pyongyang had to kow tow to the West to restore its chances of getting food supplies.
In Japan Mr Hwang had been noticeably conciliatory, saying it was time for North Korea to normalise relations with its former enemies. This may have been too much for the army chiefs, and he feared for his life on returning home.
However it was provoked, the defection is a serious blow to the Pyongyang leadership, which this weekend is to hold a massive celebration on the streets of Pyongyang for Mr Kim Jong Il's 55th birthday.
It has put a damper on that.
South Korean officials yesterday asked Beijing to step up security at their embassy. The North Koreans "are harassing us and we saw a bit nervous about that", said a spokesman, Mr Chang Moon Ik, who said Mr Hwang could face execution if he was forced to return to the north. In the meantime, he said, he was relaxing in the embassy, and reading.