Robin and his cohort receive their marks and an invitation to continue at Babel, bringing relief and a golden, carefree summer. They picnic, travel to London, and tentatively mend frayed friendships while dreaming of post-graduation voyages.

Meanwhile, Babel adopts Morse’s telegraph, expanded by Professors De Vreese and Playfair to alphanumeric code, links to the Foreign Office, and turns it into a lucrative service. Students are trained as operators; Robin takes a quiet Sunday night shift.

One night, Robin spots Ramy and Victoire in black approaching the tower. Inside, Playfair’s updated wards detect illicit purpose and ensnare them in a multiplying silver web. Robin frees Ramy and Victoire but is trapped himself; sirens draw police, who detain him in a holding room.

Professor Lovell arrives, unlocks Robin’s cuffs, and interrogates him. He denounces Robin’s ingratitude, challenges his moral arguments about Babel and empire, and then reveals a devastating claim: Griffin killed Eveline Brooke with a Chinese–English “burst” bar that exploded her chest. Lovell, shaken, makes Robin hold the bar and orders him to keep it as a reminder of who the villains are.

Lovell offers a stark choice—Babel or Hermes—and asks for actionable information. Resentful that Griffin endangered and abandoned them and fearing expulsion and ruin, Robin yields one detail: a Hermes safe room behind a rusted-looking door at St Aldate’s church. Lovell accepts this, spares Robin but warns there will be no third chance. Robin leaves clutching the deadly bar, uncertain whether he has chosen survival or betrayal.