American biologist Samantha D. Foster, better known as Sam, is headed to the Chubut Province of Patagonia to study the health of the native penguins at Punta Tombo. Her fellow passengers include Welsh tourists headed to the local Eisteddfod, an accountant seeking his runaway wife and daughter, and Arch Stuart, an amateur astronomer whose nocturnal movements begin to occupy more than her passing interest.
Local naturalist Gustavo Evans and his assistant, Alejandro López, agree to host Sam and she is quickly impressed by their determination to maintain their age-old culture despite intrusion by the contemporary world. Still, she is unable to shake her suspicions that something does not seem right. Satisfied eventually of astronomer Stuart's sincerity and propelled by anger after a penguin on the preserve dies suddenly, a man is mauled by elephant seals, and there are several mysterious sightings at sea, Sam enlists Stuart's help to figure out who or what is responsible for the tragedies.
At a critical moment, Sam becomes aware of an international threat to all cultures-no matter how isolated-and discovers Stuart's shocking true mission.