The impetuous king of Navarre and his friends, Berowne, Longaville, and Dumaine, resolve, following a rowdy turn of courtly pleasure, to spend their time in study for three years, totally renouncing the company of women. The idea of sleeping but three hours a night and allowing no women in the court seems a bit severe to Berowne, who protests the absurdity of the whole notion but agrees to sign the vow. What good can come, he reasons, when their only recreation is to be the conversation of Costard, a country fool, and on Adriano de Armado, an affected and flamboyant Spaniard.
Settling into this celibate life might have proven easier were it not for the arrival of the beautiful princess of France, on a very important diplomatic mission, with her three attractive and vivacious ladies: Rosaline, Maria and Katherine. The king, of course, must “adjust” his vow in order to take care of state business.
Even so, he insists the ladies must be lodged in a tent outside his gates. The problem is, the king almost instantly falls in love with the princess, and each of his friends follows suit by falling in love with one of the three ladies. All would like to dissolve the pact, but each believes the others are holding true to their vow.
Meanwhile, the first violation has already occurred. Don Armado finds Costard with Jaquenetta, a convenient country wench, whom Don Armado wants for himself. Now in Armado's keeping, Costard must do penance by subsisting for a week's fast on bran and water.
As this is happening, each of the four lords is busy composing passionate love sonnets and having them delivered to the lady of his choice. Alas, some of the sonnets are intercepted, some are overheard, and soon each of the lords is accusing the others of oath-breaking. Why pretend any longer, they finally reason, since it is obvious that “young blood doth not obey an old decree”? So, the vow is thrown to the wind and they openly devote themselves to the pursuit of the women. They plan all sorts of devices to woo their ladies, even to the extent of disguising themselves as Muscovites to visit the ladies' tents.
However, these ladies are not giddy girls, but sophisticated women of the world, and they are more than a little suspicious of the lords' foolish importunings. The lords get an education no university could have afforded them. These ladies are even more adept at disguises than the “Muscovites,” who are tricked into wooing the wrong women, among other things.
A messenger arrives from France to inform the princess of the death of her father, and that she must return home with all haste. The king and his friends make their plea for the hands of their ladies, fully expecting to be accepted. The ladies feel the lords are still not to be trusted. After all, they have broken their own vows of celibacy, Penance is assigned to each of the lords, and the ladies agree to reconsider their proposal in a year and a day. The ladies return to France, and, at play's end, the poor forlorn men are left to contemplate the realities of love and responsibility.