If you title a film The Secret Agent, you shouldn’t be surprised if audiences are primed for a thriller that thrives on pulsating tension. Setting his story against the holiday backdrop of Carnival, Brazilian director Kleber Mendonca Filho takes a different, more immersive approach.

Filho’s Secret Agent drips with 1977 atmosphere, replicating the loosey-goosey quality of life in the 70s. Various elements collide or coexist – music, politics, and movies. In this case, though, the abundant cruelty of Brazil’s dictatorship, then at its height, taints everything.

Early on, we meet Wagner Moura’s Marcelo, who’s driving to his hometown of Recife in northeastern Brazil. When he stops for gas, Marcelo notices a cardboard-covered corpse lying several feet from the gas pumps. Ignored by local authorities, the corpse suggests that murder has lost some of its shock value.

** **** **Although on the run, Marcelo wants to reunite with his eight-year-old son (**Enzo Nunez). The boy lives in Recife with Marcelo’s father-in-law (**Carlos Francisco). As is often the case with important information in Secret Agent, Filho takes his time revealing what happened to the boy’s mom.

Instead, we learn that the boy has become obsessed with Jaws, the popular movie of the moment. Too scary for kids, Dad thinks. The irony can’t be missed: Dangers posed by Brazil’s military dictatorship far exceed any shark threats.

In Recife, Marcelo – an assumed name adopted for self-protection – takes up residence with an ad hoc community of similarly endangered folks. They live in apartments owned by a savvy 77-year-old woman (Tania Maria) who arranges a job for Marcelo. He’ll work at an identification office, unusual employment for a fugitive, but Marcelo wants to find his late mother’s records. His family story remains incomplete.

The tentacles of the dictatorship extend in all directions. Various contract killers stalk Marcelo, who protested when the research effort he led at a university had its funding cancelled. Marcelo’s wife (Alice Carvalho) vigorously condemned the official who pulled the funding.

Marcelo has told his son that Mom died of pneumonia. Could her death have been another assassination?

Throughout, Filho uses a present-day investigation to add perspective to the main story. Two researchers transcribe old tapes that provide glimpses into Marcelo’s story. The keen interest of one of them (Laura Lufesi) sets up the film’s moving finale.

Although the film can feel scattered, the pieces are colorful and intriguing, and Filho eventually pulls them together. In what initially looks like an aside, the late Udo Kier appears as a Jewish immigrant who fled the Holocaust. In a display of stupidity and insensitivity, Brazilian thugs keep referring to Kier’s character as German.

The film’s atmosphere is heated – both in terms of temperature and mood. One of the story’s threads involves a limb cut from the belly of a shark. The rotting leg creates a tabloid frenzy; the papers write about a “Hairy Leg’’ killer, thus reinforcing an urban myth. The so-called killer seems to have a special interest in gay men, suggesting a ruse used to cover murders by police.

Bubbling with colorful detail, flashes of dread, and suggestions of collective madness. Filho’s film brims with flavors of ‘70s Brazil: spicy, hot, familiar, yet dangerous.

Stay with it, and you may experience a growing sense of outrage nestled amid a story that becomes all the more powerful by insisting that oppression doesn’t exist apart from the cultural chaos it so desperately tries to conquer.