Becks is excited to get away, to try and escape his own celebrity and to spend time with three of his best mates. Surprisingly, and a little disappointingly, it's not Giggsy, Scholesy and Roy Keane, but just some regular blokes he's met away from the football pitch - affable seeming guys with names like Anthony and Derek.
"I think you'll be surprised by how many people will know exactly who you are," predicts Victoria, his wife of 16 years, as he packs for the trip.
"If I do get recognised by a tribe in Brazil, then ... I'd be really honoured," he replies.
"What are you going to do about your hair?" She worries. "'Cos you know, humidity ..."
"Don't laugh at your mum ..." Their oldest son Brooklyn, lurking in the background, struggles to suppress a teenage snicker.
"Well what are you going to do?"
"I'll wear a hat."
Over the course of his long career, David Beckham was often characterised - perhaps unfairly, certainly unkindly - as kind of a dimwit.
We never learn his exact IQ, but he's definitely no mug. Into the Unknown is more Palin than An Idiot Abroad.
What's really important is that he seems genuinely kindhearted and humble, his appetite for new experiences insatiable, almost childlike.
"Can I have a go at filleting one?" he asks a local fisherman they spend some time with up the river from Manaus. "I've always wanted to fillet a fish."
Earlier, in Rio, he had joined in a game of foot-volleyball on the beach. "When I came to Rio ten years ago with Manchester United I really wanted to play but I never had the confidence," he explained afterwards. "I was too embarrassed to walk up and ask if I could join in. I always regretted it."
Beckham is similarly open and honest talking about his career and his family, his hopes and regrets. Maybe it's a little 'first world problems' at times, but it's hard to begrudge him. He's having the time of his life roaring through the back roads of Brazil on an old motorbike, for the first time in his adult life not being answerable to a football club.
"Do you know who he is?" one of his mates embarrassingly points him out to a group of disinterested locals at a roadside food stop. He's surrounded by a film crew, so he's obviously someone, but they just shrug. "An artist?" A huge, satisfied grin spreads across his face as he takes another sip from his tall can of beer.
The focus remains firmly on Beckham, but if anything it only serves to make the travelogue aspect of the film more compelling. We're seeing the Amazon through his eyes, or close enough, and it's hard not to absorb just a little of his enthusiasm. "This is exhilarating," he sighs, happy astride his motorbike at the bottom of a slippery mud road. "I feel like I'm 17 again."
Adjusting to life outside the bubble of professional sport is something many struggle to cope with, and some simply don't. David Beckham seemingly still entertains the small fantasy of a comeback, at age 40, every time he so much as sees a soccer ball. But he has a bigger goal to aspire to now.
"All I want to be is the best dad," he admits as the riverboat he's on chugs lazily into the sunset. "And hope that they're proud of me."
• Part One of David Beckham: Into the Unknown screens on BBC Knowledge, 8:30pm tonight. Part Two screens 8:30pm next Monday.
