The museum trip in Chapter Thirty-Five: Where Wild Roses Grow is the reward at the end of a fortnight's desperate work. After a manifestation bad enough to leave Robert feverish and unable to stand, Toby and Ben decide against isolating him further and instead spend fourteen days deliberately exposing him to controlled noise and contact — a detuned radio turned to static while he reads aloud, page by page, until the words stop swimming; hallway drills in which Ben shoulder-barges him on purpose until he can absorb the shock without cracking a photo frame's glass. The training culminates in a test with his late grandmother's bone china teacup — “If you can keep that safe, maybe you can keep yourself safe on a train” — which Robert passes, hands steady, not a drop spilled. On the strength of that one quiet moment, his uncles agree to the trip he has wanted for weeks, ever since a Natural History Museum leaflet went up on the kitchen noticeboard: a day in London, “big, loud, ugly, full of dead things behind glass.”
It goes wrong in the mineral galleries. Standing alone in front of a single stone in the ‘rocks room’, Robert feels the noise of the room spike, too bright and too loud all at once; a display stand tips, three glass rods sliding free and clattering to the floor, in full view of a woman standing nearby. That night, using a walkie-talkie link to Daniel Marsden, Robert confesses what happened, insisting his eyes went gold and that “something wanted to come out”; Daniel, unconvinced but wary of the unsecured line, shuts the conversation down with the family's established code phrase before Robert can say more.
What Robert never learns is what his uncles do afterwards: the witness's dropped wallet leads them, that same night, to her home in Luton, where they take considerably more drastic steps to ensure her silence. The museum incident becomes, in Declan Marsden's later phrasing, the thing that finally gives him leverage he did not have before — “not after what Robert did at the museum” — tightening a blackmail arrangement with Ben that reshapes much of the rest of the book.