Dr. Robert Kerans is a 40-year-old biologist whose beard has turned white due to the radio-fluorine in the water supply. Born in a United Nations settlement in the Arctic Circle, he has no memories of the world before the catastrophic solar storms. He currently leads a multidisciplinary scientific survey team operating out of an abandoned hotel in the flooded lagoon of what was once London. He feels a growing sense of futility about his climate research, convinced that no one reads his reports. Instead of working, he often delays his duties to observe the predatory mosquitoes and thermal storms, experiencing primeval dreams that draw him toward the hostile jungle environment.

Beatrice is an affluent woman occupying her late grandfather's well-stocked apartment above the flooded city. She stubbornly replicates the luxurious lifestyle and social etiquette of the twentieth century, drinking rare whiskeys by her swimming pool and reading old magazines. Despite the failing air conditioning and the oppressive heat, she refuses to join the military evacuation. She actively isolates herself from the broader survival efforts, relying on her inherited wealth and supplies to maintain a performative defiance against the apocalyptic climate.

Dr. Alan Bodkin is a biologist working alongside the military survey team. Because he is 25 years older than the rest of the crew, he personally remembers London before the floods submerged the city. He conducts his research among the ruins of his childhood, maintaining a hidden connection to an underwater planetarium. He develops the experimental theory of Neuronics, positing that the extreme tropical climate activates ancient, archaeo-psychic memories encoded in the human mind over millions of years of evolution.

Colonel Riggs leads the United Nations military envoy tasked with surveying the lagoon and preparing for the northward evacuation. He arrives at his posts heavily armed and maintains the rigid discipline of his command. He keeps his men organized and motivated despite the unbearable heat and the apparent futility of their mission. He views the ruined world through a strictly institutional lens, focused entirely on following orders and reclaiming submerged cities regardless of the moral costs.

Strangman is a pale-skinned pirate captain who commands a massive paddleboat filled with statues, paintings, and relics looted from sunken cities across the globe. He treats the flooded world as a playground for anarchy rather than a tragedy, operating entirely outside the boundaries of human laws. He mocks the ruins of civilized society by forcing his captives into theatrical rituals and parading his stolen wealth during elaborate parties.

Lieutenant Hardman is a helicopter pilot and amateur naturalist stationed at the military base. He suffers from terrible nightmares brought on by the oppressive climate, leading him to retreat entirely from public life. He becomes the focal point of Dr. Bodkin's aggressive temperature experiments before taking a weapon and making a desperate, violent escape toward the hostile southern equator.

Sergeant Macready is a dependable non-commissioned officer under Colonel Riggs's command. He assists with the daily operations of the military base, tracking personnel movements, and providing security during search missions in the flooded buildings.

Sergeant Daley serves as Lieutenant Hardman's co-pilot on the military helicopter. When Hardman abandons the base, Daley participates in the aerial and ground search mission, analyzing the sweltering geography to predict his partner's path.

Known only as "The Admiral," this man serves as the second-in-command aboard Strangman's pirate paddleboat. He manages the day-to-day operations of the crew, including salvage dives, security patrols, and medical interventions during underwater accidents.

Big Caesar is a large, physically imposing member of Strangman's crew of freebooters. He actively participates in the pirates' theatrical and cruel behavior, serving as muscle for Strangman's operation and enforcing his captain's twisted rituals.

Wilson is a soldier under Colonel Riggs's command. He takes part in the dangerous building sweep to recover the fleeing helicopter pilot, putting himself directly in harm's way during the operation.