It's a fine time to start recording our trip journal now, seven weeks into our journey, but in many ways it's also quite appropriate.

We're in Lusaka, Zambia, having arrived here yesterday with the intention of writing some articles and getting our website in order. But today was almost a complete waste of time, the whole internet having been slowed down by a virus attack, and out here in Darkest Africa it took 20 minutes to send a single email, and I received nothing and couldn't get a fast enough connection to load any web pages. And to cap it all, my computer contracted a virus from the network I was using.

More anarchy as the world outside falls apart. This evening we watched White House and FBI press conferences on BBC World TV, Uncle Sam's latest pronouncements on what the American People want done about the scourge of Terrorism in Our Backyards.

Which brings us to last Tuesday, September 11 2001, a day that has written itself into history. "Where were you when they bombed the World Trade Centre, Grandad?" "Oh, I was safe on a desert island on the other side of the world …"

As the World Trade Centre towers collapsed on Manhattan, Gisela, Shaun and I were on the back of a pick-up truck, being driven at high speed by an itinerant Scotsman called Tom down one of Zambia's notoriously potholed roads, for a rendezvous on the Zambezi River with a cast of interesting characters lost on a tropical island.

We turned off the Nakathindi Road onto a bumpy gravel track, and ended up at the riverside, a group of taditonal mokoro dug-out canoes waiting in a channel in the reeds, and the local paddlers giving us friendly greetings and loading our luggage onto their rough craft. Then followed a short haul through numerous channels between islands and over a couple of small rapids, until the sight of several riverside huts signalled we were about to arrive at our destination, the Jungle Junction resort on Zubonkulu Island, a hidden paradise in the Garden of Eden of the Zambezi River.

As soon as we put ashore, we were met by James, a young English traveller who had arrived in Zambia after crossing the continent in an old Land Rover, and who now seemed stuck on the island.

James proceeded to give us a tour of the island, showing us our huts and the swimming places and the many hammocks slung in cool shady places and the bucket showers and all the marvellous things on this beautiful tropical desert island.

Also included in the tour was a quick lesson in the island's geography and how to negotiate the many paths and junctions at night. "Just remember that all paths lead to the bar," said James, adding: "And it's traditional to get hopelessly lost on your first night, so don't worry about it."

As we approached the notorious Baboon Triangle junction, we were waylaid by a small band of the eponymous beasts, and there started a piece of Unreality Theatre that began with the bizarre, progressed through the unbelievable, and continued uninterrupted for six days. James whispered to us the little-known fact that the owners of Jungle Junction rent the island from the local baboons, and that we were enjoying a rare privilege indeed to be meeting a deputation from the landlords, and that it is customary to dance the ritual baboon dance and to down the traditional baboon spirit.

The baboons were obviously in high spirits, as they chuckled behind their fearsome baboon masks and plied us with round after round of their evil baboon liquor. Not wishing to cause offence, we threw back each new round of firewater with a new dance, and chanted toasts to the unquestionable skill of the master baboon distillers. When we congregated around the bar after our island tour, we all felt we had slipped into a Reality Warp as the merciless baboon liquor tightened its unrelenting grip on our brains.

And then the news came over the two-way radio from the mainland that hijackers had commandeered passenger jets and deliberately crashed them into the Pentagon and both towers of the World Trade Centre, causing the towers to collapse completely.

Our twisted brains could not absorb this outrageous, unbelievable event. We allowed ourselves the temporary escape route of believing that this ridiculous news was just a continuation of the Unreality Theatre; someone's idea of a really bad joke. But the group of panicked American bankers who were desperate to get off the island suggested otherwise.

And I knew in my heart that this unbelievable news of an atrocity that will change the world was true. I had been feeling very strongly for some time, since our stay in Windhoek two weeks ago, that some huge event that will change everything was about to happen. It had come up for me again, very strongly, that morning before we had broken camp and headed into Livingstone in search of the Jungle Junction office. I had felt quite clearly that morning that an event of monumental import was imminent; that I had chosen to take this trip, which has uprooted me and separated me from everything that is familiar, at a time when events in the world are set to precipitate a crisis that will change everything.

And now this incredible news. How could anyone carry out such a casually brutal and completely outrageous attack? It was beyond belief, and yet at the same time it seemed so unsurprising, almost expected. My addled brain conjured up glimpses of what the scene must have looked like in faraway New York, trod gingerly down paths of possible consequences of this act of callous infamy, until I forbid it to think about anything to do with the world outside my private desert island reality warp.

Images of pain and destruction still sniped from the wings of my consciousness, but I kept them at bay with repeated renditions of the chorus of the REM song "It's the End of the World As We Know It, But I Feel Fine".

And in between taking long-distance calls from the consensus reality, I laughed at the antics of a local businessman as he cursed Uncle Sam and everything Americans stand for. "Bastards!" he spat, eyeing the huddle of confused Americans in the boma. "Fuck 'em! What do those bastards know about AIDS? My staff are dying like flies. Fucking Americans say wear a condom. What the fuck do those interfering bastards know? Fuck 'em I say! Maybe now they'll catch a wake-up … Fuck 'em!"

The Americans were surprised by the lack of sympathy and angered by the joking and general rudeness from some quarters, but they refused to take the bait. It was left to their large, loud tour guide to protect their honour, with a brief display of aggression. It was fended off with humour and fisticuffs were avoided.