Paul Baumer tells the story of the book, as he and his classmates have ended up in the Army and are serving on the Western Front in WWII for the German Army.
The action includes periods of rest and leave when Paul draws the comparisons between men actually being alive and having emotions, etc., and then the periods of action at the front when they become little more than numbed animals struggling to survive amidst the chaos and death and gore.
At one point, Paul returns home on leave but wishes at the end of the time that he'd never come home. He realizes the futility of his emotions, feels strongly that he will never see his mother again and wishes he had just stayed at the front.
In the end Paul loses each of his friends, one by one, and then he too is killed on a very quiet day at the front. In the end he reflects that he's already lost everything, the war has destroyed him and all his compatriots and taken everything.