If we could peer back at recent history through a telescope, we'd see galaxies of unrest, from the explosive rise of ISIL to the financial crisis of 2008 to the invasion of Iraq, right through the supernova of Sept. 11, 2001, and beyond. The World Trade Organization protests in Seattle in 1999 would barely register as a pinprick of light; and yet in Sunil Yapa's vigorous if uneven debut, "Your Heart Is a Muscle the Size of a Fist," the forces roiling the world today converged in a small but heated exchange 16 years ago, illuminating who we were and where we were headed. What's past is prologue.

The novel admirably takes on big themes — the threat of terrorism, economic inequality — and treats them with nuance, following a cast of seven over the course of one day: Victor, a nomadic biracial 19-year-old; Bishop, his estranged father and the police chief; a pair of officers patrolling the streets in an armored vehicle; two protesters volunteering as medics, and an eminent finance minister from Sri Lanka.

Yapa explores his characters' back stories, but only three emerge fully formed: Victor and his father, whose near-brushes throughout the day tease out the love and loss they both feel; and King, a female advocate of nonviolent resistance, who harbors a devastating secret.

"Your Heart Is a Muscle the Size of a Fist" delves into the perils of globalism but also posits potential benefits to a war-ravaged country such as Sri Lanka. There are no easy answers. Against this backdrop Yapa's riot sequence is graphic and stirring, challenging our most basic assumptions about democracy.

His language is often vivid, as when Bishop surveys his officers: "His line had broken and he saw clumps of black in the crowd like lumps of cancer in a radiated lung, the backs of his troops' hooded forms chopping through the crowd. Batons swinging freely."

Unfortunately, Yapa lapses into sentiment as the riot winds down, his prose shading into purple: "Victor screamed … He didn't want to die. Simple things this young man loved. The colors of leaves in bright morning, how the green seemed lit from within and the sky so endlessly blue."

And as with many first books, this one struggles to escape its influences, among them Michael Ondaatje's "Anil's Ghost" and the work of Colum McCann.

But these are minor gripes. In the end, the novel sheds its political scaffolding to reveal deeper truths: King confronts her own heart of darkness and Victor reunites with Bishop in a poignant final scene. "Your Heart Is a Muscle the Size of a Fist" goes long on theme and language while coming up short on story and characterization, but Sunil Yapa's voice and ambition leap off the page. Here is a writer to watch.

Hamilton Cain is the author of "This Boy's Faith: Notes From a Southern Baptist Upbringing." He lives in Brooklyn, N.Y.