Our play opens in Messina, before the home of Leonato. Everyone is waiting for Don Pedro and his soldiers to return from a minor war. Beatrice, with teasing and witty language, lets us know that she has known Benedick for a long time and is familiar with his style and skill in word play. She is not overly impressed with either. Don Pedro of Arragon arrives with his soldiers. Leonato invites him and his men to stay a month at least and relax after the war.  Benedick and Beatrice have at it again, in their “merry war of words” and most everyone goes off to celebrate the triumphant return. Claudio has noticed the lovely Hero and asks Benedick his opinion of her. Benedick will not say what he really thinks, “being a professed tyrant to their sex” but he does admit that Beatrice is as lovely as Hero. 
Don Pedro enters and offers to woo Hero for Claudio and then approach Leonato to make the match. The two go off to prepare for the party that night.
Don John is lurking about during the party.  He and Conrade discuss why Don John is always so sad and angry.  Borachio enters and mentions the marriage plans of Hero and Claudio. Don John says, “That young start-up hath all the glory of my overthrow: if I can cross him any way, I bless myself every way.” They retire, determined to create mischief for everyone.
Beatrice and her friends enter and discuss the relative merits of men, marriage, Benedick and love. Beatrice will find any excuse to not marry, and everyone gives her plenty of ammunition to prove why bachelorhood is best. During the word play, Beatrice brings up the traditional fate of old maids—leading apes into Hell on leashes—and compares courting, wedding ceremonies and married life to dances performed at varying speeds.  “Wooing, wedding, and repenting, is as a Scotch jig, a measure, and a cinque pace.” After this pronouncement, Don Pedro and his men enter, and everyone indulges in more flirting, smiling and courting than anyone can possibly keep up with! 
As the party breaks up, Don John and Borachio sow seeds of doubt in Claudio by making him think Don Pedro is secretly wooing Hero for himself.  Claudio storms out but Benedick realizes the problem and explains to Don Pedro. Meanwhile, Beatrice brings Claudio back in time to hear Benedick call her names. We learn even more about their old relationship from this, because Beatrice seems to think she gave her heart to Benedick and did not get the same in return.
Don Pedro offers Claudio Hero’s hand in marriage, blessed by Leonato. Beatrice gets a bit caught up in the romance and is flustered when Don Pedro suddenly proposes marriage to her. She hastily twists his words around and beats a quick retreat out of the scene. Don Pedro, struck by her wit, grace and happy disposition, decides to match up Benedick and Beatrice. He is undaunted by Leonato’s warning, “O Lord, my lord, if they were but a week married, they would talk themselves mad.” They all want in on the plan, for “If we can do this,
Cupid is no longer an archer: his glory shall be ours, for we are the only love-gods.”
The pace quickens when Don John and Borachio devise their plan to disappoint Claudio in love, discredit Hero and embarrass Don Pedro. They will make Claudio think he is seeing Hero entertaining a man in her bedroom late that night, when what he will really see is Margaret and Borachio kissing on Hero’s balcony. This way, everything will fall apart and Don John will get revenge on all of them. 
Before that can happen, Don Pedro ensures that Benedick overhears his fake conversation with Claudio and Leonato in the orchard. He says Beatrice “really” loves Benedick but cannot bring herself to say anything, since she has always been so dead set against marriage. At the same time, Hero and Ursula lay the same trap for Beatrice.  In the end, both Benedick and Beatrice swear that they will return the other’s love, come what may. After all, as Benedick says “the world must be peopled.”
Later that night, Don John and Borachio throw their bomb about Hero’s supposed infidelity and unchaste behavior. Claudio decides to denounce Hero at their wedding the next day, and leave her in disgrace at the altar.
We now meet Dogberry, Verges and the town Watch. Think Mayberry RFD gone really goofy! The guys mean well but they aren’t equipped for real police work.  They do, however, overhear Borachio and Conrade taking about the elaborate plan to discredit Hero on her wedding day, and arrest the two on suspicion of misbehavior. 
The next day the wedding begins and Claudio denounces Hero, backed up by Don Pedro and Don John. Hero faints in shock and Leonato takes this as proof of her guilt.  He is ready to disown her and throw her out of his house, but Benedick and wise Friar Francis convince him that her blushes are the pain of innocence betrayed, not sin.  In the end, Leonato agrees with the Friar’s plan to announce her “death” at such shame.  “What we have we prize not to the worth Whiles we enjoy it, but being lack’d and lost, Why, then we rack the value.” Once he thinks she is dead, Claudio will realize she was innocent. As everyone leaves the church, Benedick remains behind to comfort Beatrice. They each reveal their love, and Beatrice asks a very difficult task of Benedick. At first he is reluctant, but in the end he accepts her challenge and goes of to avenge Hero’s wrong. 
Dogberry eventually gets the whole story out of Borachio and Conrade, and goes to tell Leonato of Don John’s crime.
Leonato and Antonio confront Don Pedro and Claudio, and offer to fight them both for Hero’s honor. The younger men back off and Benedick enters. Instead of making Don Pedro laugh, Benedick challenges Claudio, telling him “You are a villain; I jest not: You have killed a sweet lady, and her death shall fall heavy on you. Let me hear from you.” With that he leaves, and Dogberry enters, with the truth of the whole matter.  Don Pedro and Claudio swear to make any amends Leonato deems fair. They must do homage at Hero’s “grave” and then come to Leonato’s house the next day, to marry her “cousin.” Claudio and Don Pedro agree.
Benedick and Beatrice have some quiet time alone, but before long the lie of Hero’s shame is revealed to all and another wedding is announced. Claudio comes before Leonato and four veiled brides.  He agrees to marry one, without seeing her face.  Hero is revealed, still alive, and still willing to marry Claudio. Everyone is ready to go to the chapel again, but Benedick summons up the courage to ask Beatrice one important question. A little wrangling ensues, and finally, EVERYONE is ready to be married, happily ever after!