i agree with
Once the narrator escapes his bonds, he realizes that the demonic priests will still not let him go. The walls literally start to close in on him, and he knows that the torturers' intent is to drive him into the pit.
He tries to stay on solid ground, not wanting to fall into the pit, but at the last second, when the closing walls have left him only inches of ground, they stop moving. He is then rescued by the French General Lasalle.
This story is common to Poe's tendency towards isolated characters facing no exit from death and torture. However, in this story Poe discusses glimmers of hope and the idea of freedom in death. This contrast in theme from the demise usually experienced by his stories should be noted as particularly important in this story.