In the two weeks since he left for Vietnam, the oldest has offered up a single fragment of communication – a Facebook message consisting, in its entirety, of the word "YO". This was to be expected – I remember being his age well enough to understand that to experience independence from one's parents they must, at least temporarily, be dead to you – but I also knew my wife would not leave it at that.
"I've found him," she says one morning, prodding me awake. "He's in Laos." It's clear that she has been up for some time, possibly all night.
What she has actually found is the blog of a twentysomething Australian IT consultant called John. John is from Bondi Beach and likes running, wine, movies and opera singing. His favourite films include Star Wars, Alien and Whistle Down The Wind. He has travelled extensively through south-east Asia, and it is a mere coincidence that he finds himself on the same five-day guided tour of Laos as my oldest son.
I'm not sure how my wife found the blog, but when I went looking for it later all I had to do was type the oldest one's name and "Laos" into Google. It's a fairly exhaustive chronicle – part travelogue, part potted history, part food diary – with plenty of pictures: landscapes, temples, John sampling a glass from a clear jug of rice wine in which several bear paws are steeping. The middle section includes a long account of a boat trip up the muddy Mekong river. It's a bit like the screenplay for Apocalypse Now, but with more exclamation marks and the prices of all the drinks listed in Australian dollars.
My wife and I pore over each new upload with a combination of fascination and frustration. Our son is a very minor character in John's narrative. He occasionally turns up in a picture, one of 20 tourists seated round a restaurant table, or at the far left of a posed group in a cave, smiling, with a torch strapped to his forehead.
"He's changing his shirt," I say. "That's good."
"Are you sure that's the back of his head?" my wife says.
He's name-checked on one or two occasions, but in the most recent entries he doesn't figure at all, unless you count oblique references to "the rest of the group". We know he's seen a jug of rice wine with bear paws floating in it, but we don't know if he had any.
"At least we know he's OK," I say.
"How do we know that?" my wife says.
"Because if anything terrible happened, it would definitely be interesting enough to earn a mention from John."
Sadly the day comes when the tour ends and the oldest one and John part company. John is off to stay with his friends Lucy and George in Bangkok, which is more than we know about our son's movements.
"I think I can hack into his email," my wife says. "Give me time."
The boy rings from Vietnam two days later, catching my wife as she's getting into the car.
"How is it?" she says.
"I wish I could tell you I'm having a good time," he says, before inserting a long, provocative pause. "But there's a problem."
My wife also pauses when she recounts this bit to me an hour later, because she wants me to experience something like the bolt of terror that shot through her as she sat in the car, wondering whether he was in hospital or behind bars.
"What is it?" she says, her throat closing on the words.
There is another pause.
"The bank stopped my card," he says.
