Mona Passage is the story of two neighbors in San Juan, Puerto Rico: Galán Betances, a Cuban emigrant, and Pat McAllister, a young Coast Guard officer. During long evenings spent together talking on their Calle Luna rooftop, a deep friendship develops based on shared traumas and a common desire to heal. When Galán learns that his sister, Gabriela, is going to be committed to a mental health facility in Cuba, he plans her escape to Puerto Rico. Pat, whose Coast Guard cutter patrols the Mona Passage for drug traffickers and migrants, warns Galán that such a journey will be treacherous--perhaps fatal. Aware of the dangers but determined for Gabriela to live a full life, Galán hands over all the money he has to a Dominican smuggler based out of a San Juan nightclub, and Gabriela begins her terrifying journey.

Knowing that his cutter may be all that separates Galán and Gabriela--and haunted by the human suffering he has witnessed at sea--Pat must decide. Will he remain true to his oath, as his older brother had done in Iraq? Or will he risk his own future--and perhaps his freedom--for his closest friend?

On a moonless night, two armed vessels converge in the Mona Passage, and three lives change forever.