The whole plot of the story revolves around a hypocrite named Tartuffe, who is pretending to be a holy man.  He has fooled Orgon and Orgon's mother, but not the rest of Orgon's family.  Unfortunately, Orgon is the head of the house, and has [relatively] complete over what his family does.  He is so taken in by Tartuffe, that he decides to cancel the engagement between his daughter, Mariane, and her fiancé, Valere.  Shortly afterwards, Mariane and Valere have a very strange fight, with Dorine as the referee.  Later, while Orgon is not at home one day, Tartuffe starts hitting on his wife.  She plays coy, and is about to get Tartuffe to promise to not marry Mariane, when Damis bursts out of a closet.  Shortly, Orgon returns.  Damis accuses Tartuffe of flirting with Elmire, but Orgon refuses to believe it.  In fact, Orgon is so angry, that he decides he will transfer all his property over to Tartuffe, and wants Tartuffe to be with his wife whenever possible.  Later on, his wife tricks Tartuffe into revealing himself, while Orgon is hiding in the same room.  Orgon loses his temper, tells Tartuffe to get out of his house, and then has the nerve to be surprised when Tartuffe says it is his house and orders Orgon to leave.  Tartuffe takes off, and Orgon finally understands just what kind of a mess he is in.  You see, it turns out that Orgon gave Tartuffe some secret papers for safe keeping, which just happen to be illegal.  Later, while the family is trying to figure out what to do, Orgon's mother still won't believe that Tartuffe is evil until a policeman comes by with the order to evict them all.  Then, to make matters worse, it seems that Orgon's ex-friend Tartuffe has turned the papers over to the king, and Orgon is going to be arrested.  Valere offers to take him away, but he is too late, and a bailiff and Tartuffe enter the house.  Then, just when Orgon thinks he is doomed, the bailiff reveals he is really going to arrest Tartuffe.  You see, miraculously, the king saw through Tartuffe's disguise.  Not only is the king having Tartuffe arrested, but he has pardoned Orgon for keeping the illegal papers, because Orgon helped out in the civil war.  Orgon and his friends and family all decide to go thank the king, and after that have Mariane and Valere married.

End of play.  That's all there is to it.  Of course, it's much funnier if you actually read the story.  ;-)