After fleeing the terrors of Nazism, the Chalet School has settled into its new home in Guernsey and now the second term on its island home begins. Some old friends are delighted to return to their beloved school, but in among the new arrivals is one who has a history with the school. Melanie Kerdec was a member of a group called the Mystic M who terrorised the school some years previously, when their bad deeds culminated in the kidnapping of Sybil Russell. Now Melanie has come as a pupil to the school she detests and is determined to show that she has by no means forgiven or forgotten the past.
Even with that excitement, outside affairs cannot be ignored and the war continues to intrude as rationing affects both lessons and Guiding. An island-wide air raid drill gives the senior girls an exciting evening, and the war on the Continent leaves one mistress grief-stricken. Worse is to come as an investigator arrives to learn more about the previous term's dramatic plane crash. When he cannot promise that the Channel Islands will be safe from future conflict, those in authority must consider leaving Guernsey to find a safe place for them to live for as long as the war lasts.