This hilariously comic novel is set in the second half of World War II, and it follows the antics of Yossarian, a pilot who is based on an island called Pianosa near the Italian coast. Yossarian and his fellow pilots are shown to be subject to the whims of the generals of the army who endlessly increase the amount of missions they must fly so that nobody can ever go home. The craziness of war is shown through situations where the pilots are told that it is more important to take an accurate aerial photograph than to actually destroy the target. 

Yossarian is the central character of the novel, and he spends most of his time desperately trying to avoid flying missions, faking illnesses in order to be confined to the hospital. He hates the fact that he is trapped in a war that has claimed the lives of so many of his fellow pilots and where generals volunteer their men to fight in the most dangerous battles to gain status and prestige for themselves. One of the things that Yossarian is confronted with forcibly is his own mortality and the mortality of those around him, and this is reinforced through his repeated memories of his friend Snowden and the manner in which he died as well as his repeated references to his own inevitable demise:

One of the things he wanted to start screaming about was the surgeon’s knife that was almost certain to be waiting for him and everyone else who lived long enough to die. He wondered often how he would ever recognize the first chill, flush, twinge, ache, belch, sneeze, stain, lethargy, vocal slip, loss of balance or lapse of memory that would signal the inevitable beginning of the inevitable end.

This repeated reference to inevitable death serves to kindle in Yossarian a deep respect for the fragility of life, and therefore his determination to make the most of what life he has and to try and live that life away from the confines of war. This novel is above all else a testament to the way that war is a brutalising force and can dominate people's lives. Yossarian struggles throughout the entire novel to escape that force and to win the right to shape his own life free from the destructive chaos and insanity of war.