Catrin Quinn's job at Falkland Conservation is to protect the sea life in the Falklands' fragile ecology. Why would her goal, her passion, lie in nursing a plan to kill her former best friend, Rachel Grimwood? "In such a small community as the Falkland Islands, a missing child is unheard of. In such a dangerous landscape it can only be a terrible tragedy, surely... When another child goes missing, and then a third, it's no longer possible to believe...