What is the main conflict or problem?

I think it is possible
to classify the main conflict as one of the character vs. self variety. In this story, the
narrator must learn to control his extremeand warrantedanxieties and fears. He knows he's been
condemned by the Inquisition and that his fate must surely be death, and he must will himself
not to go crazy in this pit. At various moments, he seems to faint, overwhelmed by his fear, and
he must battle back to consciousness and critical thinking again and again. He suffers from a
"hideous dizziness" and a "vague horror" in his heart, and he
"relapse[s] into insensibility" more than once. He decides to figure out the size of
his cell and devises a clever way to ascertain its approximate dimensions. He keeps his mind
employed, distracting himself from the fears that would otherwise drive him crazy.

Later, when he finds himself strapped under the pendulum, he eventually feels the
"keen, collected calmness of despair" and formulates a plan to compel the rats to gnaw
through the ligaments that bind him. He again escapes danger, fighting to make the most of his
own mental resources under terrible duress. "[H]urried by [his] two-fold escape," the
Inquisition prepares another death for him: the walls of his cell are rapidly heated, and they
begin to close in so that he will be forced into the pit. He clings to them and screams, and is
rescued just a moment later. Had the narrator not fought with himself to maintain his sanity and
critical faculties, he would surely have perished before now, but in doing so, he manages to
prolong his life enough to be rescued by the French army.