Alek Sigley, the former student at the Australian National University who has gone missing in North Korea, was a mystery even before his disappearance made headlines.
His background is unusual. As he puts it in his blog: "Ever since I was a child, I've had a strong interest in East Asia - my father is an Anglo-Aussie sinologist and my mother is Shanghainese (from Shanghai in China).
"I've also always been fascinated by socialism - my father, like many in the humanities and social sciences, has decidedly progressive political views, my mother spent a tumultuous youth during the Cultural Revolution, and my favorite class in high school was history, where I took a formative semester studying the Russian Revolution and early USSR."
The missing man grew up in Perth (though it's not clear whether he was born there).
But he hasn't been completely complimentary about the Western Australia city: "After completing high school, I wanted to get out of my hometown of Perth (which while a lovely place, is considered one of the world's most isolated cities and was in 2000 nicknamed 'Dullsville' by Lonely Planet) and experience life abroad."
Wanderlust and an interest in Asia took him to China and to a university in Shanghai where his mother came from. "During this time, I developed a real passion for East Asian languages. I first became reasonably conversational in Japanese, and then fluent enough in Mandarin to be able to take undergraduate classes in Chinese alongside the local students at Fudan.
"At Fudan, as fate would have it, I was put on the same floor of the foreign students' dormitory as the students from North Korea. They were mostly a bit shy, but a few would chat with me when I bumped into them around campus.
"One of them, a graduate of Kim Il Sung University, was particularly friendly, and one day suggested that I visit his country to see socialism up close. Unfortunately, his kind invitation for me to visit his home in Pyongyang never came to fruition.
"At Fudan I also encountered many students from South Korea, who make up by far the largest contingent of foreign students in China's universities. This further piqued my interest in the peninsula, and I began studying Korean in 2011, eventually visiting North Korea for the first time in 2012."
He then returned to Australia, to Canberra, to study what had become his passion, the Korean peninsula, particularly the northern part: North Korea which calls itself the Democratic People's Republic of Korea.
Since the Korean War 70 years ago, the peninsula has been split in two, with the south and north both claiming to be entitled to rule the whole.
The two countries are split by the inaptly described Demilitarised Zone. It is one of the most militarised borders on the planet, with North Korea pointing 14,000 conventional big guns at South Korea and threatening its destruction with nuclear weapons. South Korea is the base for thousands of US troops on a state of constant alert.
Alek Sigley became a rarity by going on to study in Pyongyang, at Kim Il Sung University, named after the founder of North Korea. Pyongyang is one of the most repressed cities on earth. Dissent is stamped on. Opponents of the rule of the North Koran despot, Kim Jong-un, face imprisonment and even execution. Kim Jong-un had his own half-brother executed two years ago in a very public poisoning recorded on the CCTV cameras at Kuala Lumpur International Airport.
Pyongyang is a dangerous place to be a foreigner who steps out of line. In 2016, a visiting American student, Otto Warmbier, was arrested there after trying to steal a propaganda poster in a hotel. He was released a year later in a vegetative state and died soon after.
Most Westerners who get into trouble there, though, do so for distributing Bibles. Undercover missionaries sometimes get arrested and imprisoned and are invariably released after around two years, usually of hard labour in dreadful conditions.
We do not know what has happened to Alek Sigley.
All the indications are that he behaved himself. He blogged enthusiastically about the food and daily life. There is no suggestion of Christian zeal in his past.
And he got married in Pyongyang.
Of course, he may have gone missing for perfectly usual reasons and he may return from some innocent escapade.
But North Korea is not the sort of place where vanishing is easy - unless it's vanishing into the custody of the regime.