On the morning the DICOMY inspector is due, Linus insists they are not “preparing for war,” but the children treat Linus and Arthur’s room like a command center. David assumes he must hide because he is unregistered, but Sal and the others refuse; they decide David should be seen, and David chooses not to hide. The children claim they have a plan, without detailing it to Arthur or Linus.

At noon, Helen drives the inspector to the house. Arthur meets Harriet Marblemaw, who presents Rowder’s signed order granting full access and quickly shows she is condescending and intent on finding fault, including searching for “anti-government” influence. Inside, she begins a meticulous inspection of the house while Arthur warns her against planting listening devices, reminding her Zoe can revoke permission for her stay. Marblemaw declares she cannot feel fear, framing herself as impossible to intimidate.

Arthur brings her to the classroom mid-lesson. The children immediately perform exaggerated politeness, and David executes their plan by entering in a cape and posing as an adult “friend” of Arthur’s, claiming he is forty-seven. Marblemaw is thrown off, while Sal redirects attention by steering the literature discussion toward propaganda, language, and totalitarian control, provoking Marblemaw’s anger and her demand for lesson plans and a vetted reading list.

Marblemaw introduces herself by demanding deference, inventing “courtesy points,” and attempting forced obedience. She orders the children to line up and give name, age, species, and likes/dislikes; the children respond with pointed honesty and mischief. Theodore’s chirps are translated into veiled insults, Chauncey pitches a hotel investment, and Lucy’s pet scorpion crawls onto Marblemaw’s coat; when startled, Marblemaw calmly crushes it, provoking Lucy’s outrage and revealing her cold cruelty. She warns the children that any misbehavior will lead to recommendations they “will not like.”

After Linus ends the session, Arthur shows Marblemaw to the guesthouse, where Zoe is waiting. Marblemaw immediately pushes Zoe to register and threatens her against “disappearing,” but Zoe asserts her authority as the island’s guardian and makes clear Marblemaw stands on Marsyas only by permission. That night, Arthur overhears the children gathered in Theodore’s attic room, anxious but determined; Sal promises they will find each other if separated, and Lucy rallies them to meet Marblemaw’s fearlessness with their own.