Festive and lighthearted comedy, and remarkably clean for Shakespeare.
When a young woman named Viola is rescued from the shipwreck that she believes claimed her twin brother's life, a helpful sea captain puts her ashore in the province of Illyria. She soon hears of the comic plight of Illyria's Duke Orsino, whose lady-love, Countess Olivia, has rebuffed his many advances and refuses even to see him. Interested, Viola disguises herself as a boy and, under the name of Cesario, enters Orsino's service. But when Orsino employs his new servant as an intermediary between himself and Olivia, "Cesario's" simple deception escalates into a crisis of mistaken identity.
Seeing as this is a play of disguises and mistaken identities, there is the obvious moral dilemma of Viola's lies concerning "Cesario." Even more questionable is the major subplot, in which Olivia's uncle and servants collude to play a cruel practical joke on the overbearing steward, Malvolio. Malvolio is indeed an odious character and this subplot is one of the most amusing parts of the play, but their treatment of him is markedly unkind. However, it is never expressly condoned, and a character at the end comments that Malvolio "hath been most notoriously abused."
Some classical references to Roman gods, as the setting is a rather slapdash mix of antiquity (Illyria was a Roman province) and "modernity" (modern meaning Shakespeare's time). Malvolio is abused in the same terms applied to the hated Puritans of Shakespeare's day; indeed, he appears to be a caricature of the "puritanical" religious leaders whom Elizabeth I so despised.
Before the story begins, Viola is saved from a shipwreck. It is implied that her brother was drowned. "Cesario" is challenged to a duel by one of Olivia's brash suitors; Viola has no desire to fight, however, and the other party is a coward, so they both do their best to get out of the predicament without coming to blows. A duel is fought between two characters, and one man gets a sound, and deserved, thrashing.
The prank on Malvolio involves him being accused of insanity and locked away in a dark chamber; this is not technically "violent," but it is certainly abusive.
Drug and Alcohol Content
Olivia's uncle, Sir Toby Belch, is a drunkard and is up at all hours carousing; he is, in fact, the opposite of Malvolio. Though reprimanded by his niece and by her steward, he never reforms, but continues on his merry, drunken way.
Awkward situations arise from Viola's disguise, as is to be expected, but nothing untoward results. Olivia's uncle and his friend both admire Olivia's maid, Maria, and she flirts with them. For a Shakespearean comedy, there is remarkably little sexual content.
Crude or Profane Language or Content
"Mild" oaths such as "'slight" and "marry," corrupted forms of religious phrases. "Ass" is used to refer to an idiot. In general, however, there is much less crudity than one comes to expect from a Shakespearean comedy.
"Twelfth Night" is a light, festive play, more centered on jollity than on a cohesive plot. In fact, the more amusing subplot featuring Malvolio takes up more stage time than the overarching plot with Viola, Orsino, and Olivia. In several respects it bears resemblance to another Shakespearean comedy, As You Like It, with the same disguises, charades, and awkward romances. It is more centralized, however, and deals with fewer themes, so that it comes across as a cohesive whole. Lighthearted and remarkably clean, "Twelfth Night" is an extremely enjoyable comedy.