No Longer At Ease is a classic tragedy. A classic tragedy is the story of a man or woman who tries to change the world. In the end, their pride is the fatal flaw and they end up destroying themselves or becoming part of the system they had meant to destroy.
In No Longer At Ease, Obi Okonkwo, the protagonist, is optimistic and believes in his own power, and the power of young Western-educated people to change Nigeria. As a result of his optimism, he pits his idealism against the mighty system of corruption and bribery that dominates the inner workings of Nigerian government and business. He also pits his belief in the superiority of western values against his culture's traditions.
In both cases, Obi is the loser. His hubris (excessive pride) is so great that he is unable to consider the gentle criticisms that friends and family offer him as they try to steer him on a path that will allow him to live successfully in a new society. Blinded by his own belief in his ability to change the world, or at least the world of Nigerian politics and culture, he keeps heading down the path that leads to his demise.
Ultimately, Obi is unable to convince his family to accept Clara as his future wife, and he eventually succumbs to the temptation of accepting bribes.