The bike ride Adam takes through New England is the most vivid setting in the book. It's October, and it's cold, which Adam never fails to remind us of. Although everything seems relatively realistic – there's a Howard Johnson's and a lot of telephone booths (back when it only cost a dime for a call) – it's also uncomfortably abandoned. All the places he passes – from gas stations to houses to the almost-final destination of the motel – are deserted. Even though he's traveling hundreds of miles, he only passes a handful of people. This deserted setting adds to the eerie tone of the book that Cormier carefully crafts.
This empty New England setting contrasts starkly with the one we see when Adam recounts the memory of passing through these same places with his parents. They towns are not abandoned; they're beautiful and magnificent and welcoming. On a "brilliant October morning... [s]weeping, climbing curves greeted them and majestic landscapes unfolded in the distance" (30.18). And the icing on the cake is the comment from Adam's mom that immediately follows this description: "It would be lonely if we weren't together" (30.19). This contrast reminds us, as readers, that the same exact location, described differently, can be used as a completely different type of setting and can give a completely different tone to a scene.
We don't know much about this setting, which is exactly the point. It's meant to seem stark, unknown, and mysterious. Adam just calls it "the room." The only description we have of it comes at the very end of the book, after our last exposure to the room, when we learn that there are bars on the windows. Creepy! This adds to the sense of confinement we sense from Adam and sustains the mysterious nature of the place.
Adam's house in Monument seems like the typical family home: kitchen and den downstairs, bedrooms upstairs. Although we don't get a ton of details about most of the rooms, we do know a little more about the cellar, which Adam says was turned into a "combination recreation room and office, pine-paneled, with some office paraphernalia plus a Ping-Pong table and a television set" (13.13). Seems harmless enough, right? Not quite: later on we discover that this room was soundproof, "almost like a vault" (22.10). The more Adam discovers about the reality of his family's life, the more frightening and confining his home becomes. Eventually he realizes that it may be bugged.
Just like in the outdoor New England setting, there is an important contrast to consider here. Adam describes his old house in Rawlings as "nice and warm" (2.6) and immediately after notes that his new house was different, that there was "a different aura to the house" (2.6).
The hospital is an interesting setting because we see it described during Adam's bike ride, during his conversations with Brint, and once he has returned to it at the end of the book. In the opening scene, Adam passes the hospital, "high above on a hill" (1.2). In his conversations with Brint, he describes it as "[a] private home. Not merely a home but an estate" (8.1). Then, when he arrives there in reality, it is described as having iron gates painted orange, and it is "on a small hill [...], a white building with black shutters and columns in front, like a southern mansion." The hospital is the same in all of its incarnations.