Morell is a clergyman who is married to a brilliant woman, Candida. She is really responsible for much of his success. When the play opens she is returning from a vacation with her children. She brings along with her a handsome young poet, Marchbanks. Marchbanks is in love with Candida, and he tells Morell that she deserves something more than mere complacency from her husband. Morell orders the poet to leave, but at that moment Candida comes in and treats him kindly, inviting him to stay. Morell begins to have doubts; he seems old and tired.

He decides that he must leave the two alone together while he speaks at a meeting. When he returns, it seems that Candida and Marchbanks have grown even closer. The men quarrel and demand that she choose between them.   Candida decides that she must choose the man who needs her most, her husband.

Ah, my boy, get married: get married to a good woman; and then you'll understand. That's a foretaste of what will be best in the Kingdom of Heaven we are trying to establish on earth. That will cure you of dawdling. An honest man feels that he must pay Heaven for every hour of happiness with a good spell of hard unselfish work to make others happy. We have no more right to consume happiness without producing it than to consume wealth without producing it. Get a wife like my Candida; and you'll always be in arrear with your repayment.