We spend the morning trying to solve the key conundrum. The sullen guy at our car rental company is approximately nine hours away and it is a Saturday. We agree that he is unlikely to be our knight in shining armour. We go and talk to a smiling lady who seems to be part of our hostel and ask her to find us a local locksmith instead. Maybe something got lost in translation because the guys who show up a couple of hours later are carrying a hammer and chisel.

We watch with some consternation as the lads set about levering open the top of the driver’s door with a screwdriver and then force in a wooden stake. Lots of slips, lots of grunts, a fair amount of sweat, this is not the refined lock pick I was expecting. A long wire (coat hanger?) goes in and then an hour of fumbling around, poking it down into the car, trying to hit the unlock button on the driver armrest. The alarm goes off long time before they hit jackpot and this is the soundtrack to the morning. It brings various onlookers and advisors from the road, so there is soon quite a crowd.

The lads force their way in eventually, but leave some wicked dents and scratches on the roof. It is a brand new rental car and these seem very conspicuous. I pay them $20 and they lounge around the hotel drinking coffee for many hours, hooting with laughter, telling stories of hapless tourists.

We are long past checkout at this point so we agree to stay on another night in Icari.

Menna has heard of some huge sand dunes nearby which hide exotic water holes. These will be deep and clear, she tells us, like an oasis in the Sahara. They will be surrounded by shady vegetation where we may string up hammocks and relax after swimming with the frogs in the agua dulce.

So off we head, in search of this desert mirage. The rural hinterlands of Brazil’s Nordeste region is not where Google Maps excels but we don’t have any alternative. Iguanas and ibis meet red herrings and wild geese as we blunder our way down back roads that are really no more than muddy tractor tracks. We drive through wind farms and cattle farms, down white grit paths, into little shanty towns. We inch past wobbling bicycles loaded with family members, we stop for goats on the road and we end up totally lost.

Eventually after squeezing several kilometers down a narrow flint track we find ourselves at a little house made entirely from flotsam, sitting among a mess of fishing nets. Various astonished dark-eyed children peer at us from hiding places in the shadows but no adult appears to offer help or directions. I am faced with a long winding reverse back up the track. Ahead through a plastic-strewn yard is an open gateway then a blue ribbon of sea.

I make a silent decision and gun the car through the gate before Menna can tell me not to. Down a small step we bump and then we are on the beach, dodging rocks, slaloming our way down the wide hard-packed sand, wheels spinning a little. Menna is freaking, thinking we’ll get the car stuck, the kids are screaming: Go faster! Hit the dunes! Drive into the waves! I turn up the Brazilian House Grooves album which I am seriously digging at the moment. And along we fly.

Eventually the sand gets softer and deeper and I feel there is a real danger we’ll sink our wheels so I bring the car to a stop. We spill out and run around, eat a late lunch up on a dune, vaguely worried the tide will come in and cut off our escape route. We find a giant bleached turtle shell and some skeletal flipper remains. In front of us the sea stretches away to Africa and behind is a never-ending landscape of undulating sand dunes and towering white windmills. We are ants lost between endless horizons.

We finish lunch and turn the car around then drive three kilometers at full speed along the flat sand, over rivulets, waving at fishermen and kids in the dunes. Some wave back, most ignore us.

As we rejoin the tracery of cross-country trails that lead homewards (we hope), we can’t help trying a few other blind alleys in search of these mystical pools. We take service roads that lead us to rows of silent monolithic windmills. We go and lie at the base of one, looking upwards, watching huge blades whirling silently against the hard blue. With no peripheral reference points this creates an optical effect, it feels like we are rotating too, lying on shifting ground, moving through immense orbits. Gravity ripples and slips. Stretched out in the dust we gently swing like Focault’s pendulum, proving the earth’s motion.

“The lakes in the dunes?” asks the smiling lady when we get back to the hotel, “Oh, but they are only there in the wet months. Perhaps in December you will see them – if you come back!”

Over a takeaway dinner that evening we teach the kids the meaning of the word quixotic: Committing yourself whole-heartedly to wild escapades, we say. Being idealistic but naïve. Chasing impossible dreams. Tilting at windmills.