Irish sea captain Johnny O'Scanlon hates the idea of closing the family shipping business, but there's no other way to raise the money he needs to pay the medical bills for his grandfather, who raised him after his parents died under mysterious circumstances. To secure his grandfather's future and his own, Johnny has to sell the last, beloved ship of his fleet, the Marigold, for scrap—but what his future holds without the sea, Johnny can't imagine.

When his grandfather's former IRA compatriot, Dillon O'Connor, offers Johnny one final consignment—to deliver a cargo of construction materials for a UN project in the Congo—the offer seems too good to be true. And it is. The last voyage of the Marigold pits Johnny against corrupt officials, threats from the locals, and treachery from within his own crew. Barely escaping with his ship and his life after a gunfight with pirates, Johnny wonders just what in his hold men seem willing to kill for. But when he can't trust anyone—especially his alluring cook, Miranda, who seems all too willing to learn his secrets—Johnny has to outwit Dillon O'Connor, solve the mystery his grandfather has spun around him, and deliver his cargo, and the Marigold, before it costs him his life.