The Chesapeake Bay rarely freezes, but when it does, the ice halts global shipping companies and Smith Island fisherfolk alike from making a living. With their deadrise workboats locked in ice at their piers, the people of Smith Island take to the frozen wastes on foot, on skates, and even on golfcarts, to experience this freak weather phenomenon. Blackshaw is not immune to the lure of the ice, but on his sightseeing trek, he discovers the frozen corpse of a woman. Blackshaw and his neighbors bring the dead body to an abandoned restaurant on Smith Island, and place the remains on an old picnic table inside. Only then do they realize the woman was shot at close range, then tossed into the Chesapeake days before the bay froze.

A neighbor boy dashes into the makeshift mortuary with shocking images captured by his drone's camera. There are eight more corpses still out there frozen in the ice. Blackshaw and his neighbors bring the other bodies inside. Several of them wear life preservers labeled Penelope, which is the name of a massive Liquid Natural Gas transport frozen in the Chesapeake's main shipping channel. Every corpse shows signs of foul play.

As night falls, Blackshaw and Knocker Ellis decide to patrol through the worsening blizzard to the ship to investigate. Before they leave, LuAnna finds a microscope slide stashed in the first corpse's clothing. The slide contains a blue fluid, which they quickly identify as a sample of horseshoe crab blood. They soon tie the murders of the Penelope'screw to a plan set in motion by Big Pharma which wants to destroy the entire Chesapeake Bay fishery.

Blackshaw's frenemies from the FBI, Agents Molly Wilde and Pershing Lowry, soon join the mission, which involves keen detective work, as well as a several bloody skirmishes aboard an LNG tanker wired to explode. Blackshaw, LuAnna, Ellis, and friends must defuse the plot before Washington, D.C. is devastated, and life in the Chesapeake Bay is poisoned for decades to come.