17-year-old Geneviève lives with her widow mother, who owns a chic but financially embattled umbrella shop in Cherbourg. She and Guy, an auto mechanic, are in love and want to marry. But her mother does not agree: she thinks Geneviève is too young and Guy is not wealthy enough.
The two are seperated when Guy receives his draft notice for a two-year tour of combat in Algeria. On his last night in Cherbourg they spend the night together. After he has left, Geneviève finds out that she is pregnant. She still loves Guy, but receives hardly any news from him. So she must choose between waiting for Guy's return or accepting an offer of marriage from Roland Cassard, a wealthy diamond merchant, who fell in love with her at first sight and promised to bring up the child as his own.
But then a surprised Guy returns. He finds another loving wife but he suffers such like Geneviève about the missed opportunity.