After accidentally discovering that he was a mutant time traveler, Hunter McGill and his wife Maggie (a "normal") time-travel together as much as possible. They also sometimes jump through time and space with their friend from the future, Halona Mad Plume (also a mutant time traveler), and Hunter's old army boss and friend, James "Jimmy O." Owens, another "normal." After a particularly dangerous close call during a jump to the past, Hunter reappears with an Ice Age guest literally in hand. The visitor from the ancient past arrives empty-handed but still carrying a lot of emotional baggage. With his arrival, the time-traveling team members find themselves thrown into a temporal tempest that only time (and a lot of sweat and luck) can overcome.