Apprentices Leo and Sam are introduced in the Wrapping Annex, tasked with sealing packages for delivery. They discover the packages for the North Peak route are significantly underweight, indicating an inventory substitution crisis. Leo, using his keen observational skills and a simple piece of salvaged metal, manages to access a restricted cache of Grotto Seals. They find the seals vibrating and humming, indicating active resonance absorption even in storage. The discovery shifts their focus when they uncover a mysterious symbol etched into the wall behind the cache, suggesting the inventory issue was a deliberate distraction from a deeper structural threat beneath the Annex, which is now generating a high-pitched whine.