As soon as dusk began to fall, the area around the Grand São Luis Hotel started to feel seedy.
We walked quickly until we noticed, a few here, a few there, student-aged persons walking, even skipping, down the road.
The heritage-listed centre of this steamy Brazilian city dates from the early 1600s and was occupied by the French, then the Dutch, before the Portuguese gained sole control of Brazil’s north-eastern region.
As we headed towards the commercial district more moços and moças (lads and lasses) appeared from side streets; they moved in the same direction.
Pairs greeted pairs and formed groups advancing on some unseen destination. Some, I noticed, carried rolled up cardboard.
In the previous few weeks we had seen the news reports: thousands and thousands of people, mostly young, were protesting all over Brazil.
The protests began against a rise in bus fares in Sao Paulo, Rio de Janeiro and some regional centres but became an outpouring of national frustration by young Brazilians at the millions of reais the government was spending on soccer.
It was a year before Brazil was set to host the World Cup and another international competition, the Confederation Cup, was testing out the shiny-new multi-billion dollar stadiums across the country.
The protests were timed to coincide with—and if possible disrupt—that competition. There was no international stadium being built in São Luis but the students were not letting that stop them.
The placards carried by the young people were pro-education or anti-corruption. Brazil’s political and judicial systems have long been run on bribes, rorts and kickbacks.
The previous year the topic hit the international media when 25 senior government people were convicted of using public funds to buy votes, ending an eight-year scandal known as Mensalão, which derives from the Portuguese words for ‘big monthly payments’.
Three congressmen lost their seats.
The trial didn’t solve the problem though, and the building program for the World Cup and for 2016 the Olympics has provided another arena for the powerful to line their pockets.
It was humid and getting dark as we walked, watching more and more students trickle through the side streets to join the veritable human river that flowed down the Rua Silva Maia.
Shopkeepers were shutting the metal gates and grates that separated their shops from the streets, swiftly, firmly, with purpose rather than panic.
There were fireworks — there are always fireworks for an event in Brazil — telling people to come: Bang-Bang! Bang-Bang! Now-Here! Here-Now!
The protesters blew whistles, beat drums. They made more noise than fans at a football final although the atmosphere was not dissimilar.
There was a slight euphoria, even a sense of fun.
The young women had long dark hair, were dressed in shorts and pastel-coloured shirts. They waved their cardboard slogans with both hands.
We all wore thongs — the official footwear of the north — with Havaianas being the students’ preferred brand.
Some had smeared war-paint in two slashes across their cheekbones. They chanted. The words were foreign, lost in the din, but the cadence was familiar.
That chant I know from my own protesting days — for free education, against nuclear war — in the 1980s: ‘The People. United. Will Ne-ver Be De-feated.’
Whistles shrilled; drums beat.
A young man approached, saying something I couldn’t quite make out over the noise, before I realised he was apologising: he was about to take a piss against the wall next to me.
More than a few blocks later, the protest culminated outside the Palácio de la Ravardière which houses São Luis’ City Hall.
Its white-painted stone walls had been recently scrawled with graffiti. The slogan ‘Get Out Globo’ is a popular one in Brazil, and refers to the country’s dominating media company.
Like so much in Brazil, the protest was eclectic.
The colonial building was one of many that line the plaza near our hotel. Suddenly, as we emerged from a cobbled laneway, people began running.
The panic was slight but contagious. I felt a clutch to my heart. Police think little of using tear gas or rubber bullets against protesters in Latin America.
I had been caught in tear gas before during student protests in Chile. So we ran too, straight into the smoothly-paved driveway of the hotel.
I brandished our room key, all too aware that the security guard sported a pistol in the holster on his hip and I really, really wanted it to stay there.
A black helicopter buzzed overhead, like a blow-fly over a carcass.
We crept up to the road and stood for a moment or two before the protesters scattered again.
In the lamplight I could just make out silhouettes of uniformed horse-riders cantering across the lower end of the plaza.
There was an odd feeling amongst the crowd, not really panic, more accepting than that. As if this was part of the play.
The rules were known, the roles clear. This is what Brazilian Military Police do; they are state forces responsible for, among other things, pubic order.
Sometimes they feint and sometimes they really do shoot tear gas — or rubber bullets that cause hideous bruises — at protesters. Perhaps that night they were simply glad for the training or unwilling to waste resources, after all that’s really what the protest was about.
Beer and cola sellers pulled wagons amongst the crowd, which had broken up into small chatting groups.
Sitting on the steps of the old stone church, a group of moças held an animated discussion, waving their nailed-painted fingers.
Their words were drowned out by the helicopter which had its powerful spotlight tracking a course over the people below.
I imagined the young women were discussing what they were going to do that night for, as is so often the case in Brazil, there was a festival on. But perhaps they were discussing Satre and Beauvoir.
Resting on the wall next to us, a young couple bend their heads together, sharing a cigarette.
Figures broke off in pairs and quartets like calves from a glacier.
Less than half an hour later it was all over but for a few die-hards shouting parting slogans and shaking the odd fist at the troops.
And when enough of the protesters had wandered off down the side streets, the pop-corn seller, too, turned his wagon and headed for home.