Channelling the urban restlessness and vibrancy of São Paulo, Marcelo Caetano’s bracing drama centres on those who live on the fringes of an ever-changing metropolis. Fresh out of juvenile prison, 18-year-old Wellington (João Pedro Mariano) finds himself at a crossroads; abandoned by his parents, the wide-eyed young man finds solace in the arms of others. On an evening out with his rowdy group of queer and non-binary friends, Wellington crosses paths with Ronaldo (Ricardo Teodoro), a hunky, charismatic hustler more than twice his age. Bathed in the flickering glow of a neon-lit porn cinema, their first meeting is sensuous and erotic, with an edge of danger. Ronaldo quickly introduces Wellington to the shadowy world of sex work and drug dealing.

Caetano depicts Wellington’s new life of crime with tender empathy rather than as a sensationalist cautionary tale. Now going by the name of Baby, he approaches his transactional encounters with cocky bravado and touching naivety. To his customers, Wellington lends not only his youth and his body, but also moments of care. In the feverish excitement of São Paulo, filled with bustling alleyways and colourful shopfronts, there’s a gnawing loneliness, as unmoored souls cling on to one another for momentary bliss.

Ronaldo is both a lover and a protective father figure to Wellington, but their relationship is derailed by jealousy and economic precarity. Threats from shady figures in the underworld pale in comparison to the fear of state surveillance and incarceration, represented by the hovering figures of police officers on patrol. Baby is most powerful as an astute portrait of the lost people who have fallen through the cracks of the system. The streets might be fraught with peril, yet they are where they can find their own family, too.

● Baby is in UK cinemas from 12 December.