A senior couple's long-planned dream vacation slips out from under them — along with any financial or moral standing — in a strong fifth feature from former Karlovy Vary Crystal Globe winners Kristina Grozeva and Petar Valchanov.

How much dirty cash can pass through your hands before your soul is stained? Gosha (Ivan Savov) and Marina (Tanya Shahova), the struggling sixtysomething couple at the center of “Black Money for White Nights,” believe they’ve found the right balance: Professional bribery is the way of the world, as they see it, and they engage in just enough of it to keep their heads modestly above water. But when they karmically find themselves the victims of a financial scam, they haven’t a leg to stand on, either ethically or economically, and the axis of their lives is set askew; turns out you can’t play the corruption game only when it suits you. Bulgarian filmmakers Kristina Grozeva and Petar Valchanov aren’t unsympathetic to their flailing characters in this sharp, escalatingly sad black comedy, but they aren’t sparing either.

Premiering in the Crystal Globe competition at Karlovy Vary, “Black Money for White Nights” is the latest in a run of recent Bulgarian films to unpick compacted layers of social inequality and systemic rot in the country today — it would pair particularly well with Stephan Komandarev’s thriller “Blaga’s Lessons,” a comparably bleak and compelling portrait of a desperate civilian slipping into criminality that won the Crystal Globe three years ago. Grozeva and Valchanov, as it happens, won the same prize for their 2019 film “The Father,” which shares a streak of mordant gallows humor with their latest. It’s hard to laugh much, however, as these two easy marks — hopelessly naïve if not quite innocent — walk into ruin.

Gosha and Marina are, to an extent, archetypal figures, representative of a Bulgarian class and generation most susceptible to a national culture of corruption, while their economic woes and errors stand in for those of a wider population ill-protected by the government and other negligent institutions. But “Black Money for White Nights” is still a humane, specific work, more audience-friendly than the filmmakers’ last feature: the arch, Maria Bakalova-starring political satire “Triumph,” which was their third film to be picked as Bulgaria’s international Oscar submissions. (It wouldn’t be surprising if this was the fourth.) There’s unsentimental compassion in the new film’s gaze, warmed by Shahova’s and Savov’s vulnerable, recognizable performances in pleasingly nuanced roles.

But the year is 2022, Russia has just invaded Ukraine, and suddenly the possibility of traveling there as a tourist looks distinctly far-fetched. The vulgar travel agent who books their trip is suspiciously quick to assuage the couple’s concerns: When, on their planned day of departure, the entire booking turns out to be bogus and the agency has vanished, they are blindsided, but we are not. Scammed out of their life savings, with the police taking scant interest in their case, Marina and Gosha process their devastation in opposite ways. Where she turns inward, concluding that their misfortune is punishment from God, he seeks vengeful solutions that only imperil them further.

Grozeva and Valchanov’s hard-nosed script deftly gestures at a vast national ecosystem of crime and economic exploitation in which Marina and Gosha are but minuscule organisms near the bottom of the food chain. But the dramatic meat of “Black Money for White Nights” is closer to home: The film is most compelling as the fallout of the scam exposes the foundational cracks in the couple’s long, childless marriage, along with various lingering deceptions and resentments. And as Marina’s younger sister Lucy (a superb Margita Gosheva) attempts to help her out of her bind, a personal and cultural chasm emerges between them too: Marina’s insistent Russophilia, it turns out, is not just a politically incorrect eccentricity, but a poignant kind of self-delusion.

The filmmaking supports this character-oriented work with subtle technical brio. DP Alexander Stanishev’s grainy, fluid camerawork cleaves to Marina and Gosha with vérité-style restlessness, whether following them through cramped domestic spaces or a whirling Pride parade in central Sofia, while editor Yorgos Mavropsaridis (a Yorgos Lanthimos regular) tracks these grim events with brisk, grounded efficiency that still accommodates a sense of spiraling absurdity. Carefully detailed production and costume design captures their quaintly dated aspirations — whether in the thrifted animal-print fashions that Marina picks out for her grand tour, or the tired birch-forest wallpaper that dominates their living room, in yet another nod to her supposed Russian ancestry. “Black Money for White Nights” may gently mock the couple for such choices, but this wryly intelligent, gradually crushing film isn’t out to destroy them: That’s the job of the system.