Although Christopher's mind goes to the edge of the universe, the scope of Christopher's physical world is sorely limited—at least in the beginning. Before his trek to London, Christopher seldom goes anywhere except home, his special school and the store on the corner to buy sweets. As he begins to investigate Wellington's death, however, he begins to expand his horizons by interviewing his neighbors. During his trip to London, though, Christopher's environment explodes. Every step is a new place, and every destination is a monumental accomplishment, attained through colossal adventures, at least when viewed through Christopher's eyes. Significant places include the Swindon Train Depot, the train's toilet, his near-toilet hiding place, London and Mother's flat.

Significant objects include the murder weapon, which is a three-pronged garden fork, Christopher's Swiss Army knife, with "a saw blade that could cut off a finger," the purloined letters...