Matthew is a fearless explorer, adventurer, and survivalist, particularly in the coldest regions of the world. When he learns of the unexplained disappearance of his friend, Dr. Tarkovsky, he sets off with a search-and-rescue mission with his faithful Siberian husky, Caesar.
Vesna is the founder of Voltan Technology Corporation, which has become the preeminent provider of robots in Europa and beyond. When she learns of the mysterious meteorite and the missing expeditions that followed, she sets off with her robotic Arctic fox, Voltan, to search for new technology.
Anna is a merchant and a diplomat, always in search of ways to help others. When she learns of the disappearance of multiple expeditions and new troubles that plague the people of Siberia, she sets off with her trusty companion and war hero, Wojtek.
Gunter is a world-famous soldier, leader, and tactician, though he finds himself with a lack of purpose during times of peace. When he learns of strange attacks and lines drawn in the snow of Siberia, he heads north with his aging dire wolf, Nacht.
Akiko is an academic who in recent years has devoted herself to the study of ancient artifacts and lost civilizations that predate humankind. When she hears rumors of strange occurrences in Tunguska that follow the meteorite crash, she sets out to investigate with her clever monkey, Jiro.
Olga is a former intelligence officer who has rejected the warmonger ways of her homeland, instead finding refuge in remote towns and villages. It is in one such village that she originally met Dr. Tarkovsky. When she learns of his ill-fated expedition and those that followed, she sets off to find them with her Siberian tiger, Changa.