Marcelle de Barthas is young French widow, who since her husband’s death some seven years previously, has lived a secluded life in her country house, with her four children. The eldest one, Emmy, is a beautiful and pure young girl of seventeen, who tentatively believes she has a calling to the religious life. The second child, Bertrand, aged fifteen, has been sent to England for an exchange holiday with a young English boy, Harry Fanning, and when the play opens, the French children are excitedly awaiting his arrival. Also living with the family is a French governess, and a tutor, Blaise Lebel. Lebel has a sombre power over the family, and it is the ‘intrusion’ of Harry that sets in motion in him a wave of resentment and fear.