By the time we arrived at Ali's front door, the clock was running down on our Cinderella liberty.

In 20 minutes, at noon sharp, our cruise ship would leave Esna to sail along the Nile for Luxor. It had taken Ali the better part of an hour to deliver me and my friend Chris to his family home; we were now so far off the tourist track there was no way we would be able to find our way back through the labyrinthine streets on our own.

Ali gestured toward a battered door that stood slightly ajar. A clutch of people–Ali's friends and family–leaned awkwardly on either side of the frame. I could see the corner of a woven carpet covering a dirt floor; beyond that was darkness. "Come in," he said. "Come in!"

Chris looked over at me and raised an eyebrow.

Fingering the laminated card that told us what to do should we find ourselves left behind on the banks of the Nile, I felt my heart slamming in my chest and wondered what I was so afraid of.

Chris is a big traveller. He likes to find his own way in a new town, get off the beaten path, and see people in their day-to-day environment. He thinks it builds compassion to allow himself to feel the discomfort that comes with being a stranger in a strange land. He's a trusting sort of fellow, but over the years, he's learned that there's a fine line between being open to new experiences and being an idiot.

For example, three years ago in Uganda, he found himself near that country's border with the Democratic Republic of Congo. "There had been some hatchet killings recently, and everyone told me not to go over," he said. "But I went, and it was very weird: like walking into a troubled town in the Old West. Everyone just stared at me. I picked up my camera to take a picture and immediately someone put a rifle in my face and said, 'No, no.'

"That was an extreme case; usually the you're-not-wanted-here vibe is a lot more subtle. But when you feel it, it's definitely time to turn back."

The small white cruise ships were moored four deep at Esna. They looked like floating wedding cakes. Some were heading south to Aswan; others were bound north to Luxor. They all found themselves bottlenecked at Esna's lock, so they took their place in the queue and waited quayside for their turn to pass through.

Most of our fellow passengers took the delay as excuse to nap–we had been up at sunrise to visit the temple of Horus–but Chris and I and a few others had badgered the crew into letting us go walkabout for a few hours. Our group had been kept on a tight schedule, watched over by armed tourist police, and there had been little opportunity to interact with the locals.

We had just cleared the gangplank and were revelling in our hard-won freedom when a boy of about 14 wearing a grubby brown robe and a black-and-white-checked head scarf appeared at Chris's side.

"Spices? You want to buy spices?" he asked in heavily accented English. "I know very nice spices."

"No thanks." We kept walking along the quay, past rheumy-eyed men smoking sheesha and skinny goats feasting on gutter garbage. The boy walked backward, facing us.

"Market, you want to go market? Perfume? Spices? I know a shop. I take you."

We kept walking.

"What you want? Tea? You want tea?"

"We just want to walk," said Chris.

"Okay," beamed the boy, "I take you. I am a guide." He pulled a plastic card from a pocket in his tunic and held it up to my face.

In Egypt, tour guides are licensed by the state. Ali's ID was clearly fake: his glued-in photo showed him wearing a Santa Claus hat, but his entrepreneurial spirit was infectious, and Chris and I agreed to let him show us around for the next two hours.

I am forever inviting travellers home for dinner. My parents did it, and it annoyed me as a child when foreigners showed up at the dinner table like they were part of the family. But now I see it as a way to travel when I can't travel. I get to chatting with a young ESL student from Japan on a bus and the next thing I know, I'm inviting her to come over for supper and bring a friend.

Until I stood in Ali's doorway, I never quite grasped why sometimes my potential guests declined my generous offer.

The dirt streets quickly narrowed as we moved away from the riverside. We had switched to French within a few minutes of meeting; I didn't speak Arabic, and Ali's rudimentary English was limited to the finer points of spice sales. He chatted easily as he wended a circuitous route through the warren of open-fronted shops and homes. He clearly enjoyed being seen in the company of tourists and waved ostentatiously when we passed people he knew: a wizened tinsmith, a middle-aged tailor at an ancient sewing machine, a gypsum merchant several years Ali's junior.

As the dim maze closed in around us, though, our presence began to feel like an intrusion. We felt the eyes on our backs. At street level, men watched with stern faces; from above, unveiled women peered through wrought-iron window screens. Children stopped kicking around a deflated soccer ball to stare as we passed–and then swarmed noisily around us with hands outstretched.

Ali was determined that we meet his family, but as we wandered further into his private Egypt I felt a mounting anxiety. We didn't have a clue where we were. Ali was vague on how much farther we had to go. We knew the ship would leave without us. We hadn't told anyone where we were going.

When Ali's pudgy arm circled my waist, I slapped it away and told him it was time to go back–now. He just smiled and kept walking.

My teenage daughter cycled through rural China this summer. She told me that when she felt overwhelmed by a certain situation, she would recall a concept put forth by a favourite middle-school teacher, that between your comfort zone and your scary zone is your growth zone–and that that's the place you want to spend as much time as possible when you travel.

When I think back to Esna, I'm pretty sure I was red-lining in the growth zone.

I did not cross Ali's threshold. I could see Chris was keen to go in, but he didn't want to leave me alone in the street. So instead we shook hands with Ali's mom and dad, uncles and aunts, cousins and grandparents, and passed around pens and balloons to the children and snapped a bunch of photos and made the kids giggle by showing them their digital selves. And then, visibly sweating, we ran a gauntlet of begging children in the direction we thought the river might be.

Ali was in no rush to return us. He was indifferent to our exhortations to hurry. Finally we explained we wouldn't pay him if we missed the noon departure. He shooed off his grabby peers and quickened the pace.

It was exactly 12 o'clock when Chris handed Ali some bills and we ran down the crowded concourse to the waiting ship. We were both breathing hard. As we stepped back into our comfort zone, the gangplank was raised behind us–a handshake withdrawn. I waved goodbye to Chris and headed for the quiet of my cabin, relief and regret trailing in noisy conversation.

Access: Nile cruises run year-round; you can explore options at the Egyptian Tourist Authority Web site, www.egypt.travel/