Viola and her twin brother Sebastian have been shipwrecked off the coast of Illyria. Each believes that the other has drowned. Viola disguises herself as a boy and, under the name of Cesario, enters the service of the duke Orsino. The duke sends Cesario to woo the lady Olivia on his behalf, but Olivia falls in love with the lovely 'boy'. Viola/Cesario, meanwhile, has fallen in love with Orsino. Sebastian is saved by the sea captain Antonio and he too arrives in Illyria. Malvolio, Olivia's steward, disapproves of the other members of her household - her kinsman Sir Toby Belch, his friend Sir Andrew Aguecheek and the jester Feste. Led by the ingenuity of Maria, Olivia's waiting-woman, these three plot Malvolio's downfall. Olivia meets Sebastian and, mistaking him for Cesario, arranges for them to be secretly married. Further confusion follows upon mistakes as to the identity of the twins. Orsino is furious at the apparent falseness of his page, but, with the eventual meeting of the twins, true identities are revealed and Orsino recognizes his love for Viola.
The play mirrors the events of Alençon's proposals to marriage with Elizabeth. De Vere casts himself as Feste - the jester who comments on the various events. Olivia is the witty and charming female ruler whose hand in marriage is sought. The suitor Duke Orfino is Alençon. He sends a series of messengers. Olivia rejects the first messenger, and falls for the second. Eventually, Duke Orsino arrives, as Alençon did in the summer of 1578. Feste (de Vere) comments on the events. Feste also entertains Duke Orsino with a love song, presumably acknowledging that de Vere entertained Alençon during a visit in September 1579.
In the play, Olivia court consists of a number of characters based on individual's in Elizabeth's court around 1579 - Maria (based of de Vere's sister Mary), Sir Toby Belch (based on Peregrine Bertie), Sir Andrew Aguecheek (based on Sir Philip Sidney, Bertie's best friend), Malvolio (based on Christopher Hatton).
The play pokes fun at Aguecheek, who pretends to be sophisticated but makes one verbal pratfall after another. De Vere was not fond of Philip Sidney. However, the play gives a two-sided portrait of Aguecheek. Sir Toby Belch likes Aguecheek, and speaks of him as an ideal courtier who "speaks three or four languages word for word without book". Aguecheek tells Belch, "I am a fellow o' the strangest mind I' th' world: I delight in masques and revels sometimes altogether." In short, he is a lover of the arts. Sidney was an artistic rival of de Vere, but one who took exception to some of de Vere's dramatic techniques, for example compressing entire lives into a two hour time period, or shifting moods and settings without explaining each step to the audience.
In Twelfth Night, Aguecheek provokes a duel, then tries to wiggle his way out of it. In September 1579, Sidney and de Vere got into an argument over a tennis match. Sidney left in a rage, preparing to fight a duel. Elizabeth forbade the duel.
In 1579, de Vere was not living with his wife Elizabeth, to the consternation of Elizabeth's father Burghley. In Hamlet, Polonius recites a list of dirty tricks to discredit a courtier, one of which involves a smear campaign over a "falling out at tennis". The suggestion is that de Vere's argument with Sidney was used by Burghley to smear de Vere.
In Twelfth Night, Malvolio is a self-infatuated "clodpole". Sir Toby Belch calls Malvolio a "rascally sheep-biter". Hatton in 1980 wrote a letter to Elizabeth describing himself as "Your Majesty's Sheep. The letter included a veiled reference to de Vere. It noted that the Sheep has no tooth to bite: where the Boar's tusk may both "raze and tear". The Boar was the animal on de Vere's heraldic crest, and around that time, de Vere was raising hell.
Also in the play, Malvolio comes across a prank letter intended to make him look foolish. The signature on the letter is "The Fortunate Unhappy" - a play on Hatton's Latin pen name "Felix Infortunatus" meaning the "Happy Unfortunate".
In the play, Malvolio is imprisoned, and denied pen, ink and paper. Feste cross examines Malvolio, who only wants a candle, pen, ink and paper.
MALVOLIO: Good fool, as ever thou wilt deserve well at my hand, help me to a
candle and pen, ink and paper ... Fool, there was never man so notoriously abused. I am as well
in my wits, fool, as thou art.
FESTE: But as well, then you are mad indeed if you be no better in your wits than a fool.
In 1580, Edmund Campion, who had been one of de Vere's commencement speakers at Oxford in 1566, had returned from Prague. The pope had advocated the assassination of Elizabeth, and the antipapists in Elizabeth's court (Burghley, Walsingham, Leicester, and Hatton) wanted Campion tried for treason. He was subsequently imprisoned and tortured so brutally on the rack that he could not raise his right hand to be sworn as a witness. He was given two hours to work on his courtroom defense, and denied pen, ink and paper. De Vere's secretary Anthony Monday served as witness at the trial. In Twelfth Night, de Vere put Hatton in Campion's position.
The play portray's Sir Toby Belch as a mischief-making, dueling, drinking, quarrelsome swordsman - a slight exaggeration of Peregrine Bertie. Belch is a companion of Aguecheek, as Bertie was to Philip Sidney. Belch gets into two sword fights that the cowardly Aguecheek evaded.
In Maria's first scene on stage, she is greeted, "Bless you, fair shrew." Maria was lady in waiting to the romantically entangled Olivia. De Vere's sister Mary was lady in waiting to the romantically entangled Elizabeth. Like Mary to Peregrine Bertie, Maria is ultimately loyal to Sir Toby Belch, who boasts, "She's a beagle true bred and one that adores me."
In the play, Antonio and Sebastian are two friends reunited when the latter washes ashore after it was believed he had perished at sea. In the late 1570s, King Sebastian of Portugal went missing in action after leading a crusade against Morocco. He left the Portuguese throne vacant, with no heir in sight. In 1580, King Philip of Spain took control of Portugal. A strong Spain under King Philip created fears that a Spanish armada might attack England. If Sebastian were washed ashore, he could take back the Portuguese throne. Many in England championed Antonio, a pretender to the English throne who had visited England in 1580. He found supporters in Sidney (Aguecheek) and Hatton (Malvolio).
In the play, Feste begs for three gold pieces, saying, "The old saying is the third pays for all. The triplex, sir, is a good tripping measure. Or the bells of St. Benet, sir, may put you in mind - one, two, three." Feste ultimately gets his cash.
Thomas Churchyard was a soldier and poet, and had been in de Vere's service off and on since the 1560s. In his 70s, he had entered into a lease with Julia Penn, a London landlady, who had apartments. De Vere guaranteed the rent, but backed out of paying. Churchyard sought refuge in a nearby house of worship. The Church of St. Benet's of Paul's Wharf was near the apartment.
In the summer of 1575, de Vere was in Venice. Following the coast of present day Croatia, one would come upon the city state of Ragusa in the area known as Illyria. Ragusa is now known as Dubrovnik. By the 16th century, Venetian ships regularly visited Ragusa, which was seen as a safe place for restocking. Ragusa has a place in de Vere's family history. King Richard I shipwrecked near Ragusa, built a cathedral in the city to thank God for delivering him from disasater, continued inland, and was captured. The first Earl of Oxford contributed to paying the king's ransom, and his brother may have accompanied the king. In the 16th century, Ragusa was a place where Slavic, Italian and Ottoman cultures came together. The play is set in an unnamed Illyrian city. A shipwreck off the coast leads a band of travelers to fall in love with the city. Olivia criticizes boorish Toby Belch by saying he is only "fit for the mountains and the barbarous caves, where manners ne'er were preached". The city was most likely Ragusa. There are mountains around the city's harbour and there are networks of caves were pirates and criminals attacked shipping. De Vere likely visited Ragusa, and this visit allowed him to describe it in the play.
The plot for the play is based on the an Italian play by Alessandro Piccolomini called The Deceived (GI'Ingannath). In the Italian play, there are brother sister twins. The sister is in love with a nobleman who is wasting his time on someone else. The sister disguises herself as a male servant, and carries letters between the nobleman and his lover. The twin brother was supposed to be dead, but arrives on the seen and solves the problem by falling in love the nobleman's lover. The twin sister then snags the nobleman. De Vere wrote a letter from Siena dated two days before the Italian play would have been performed. He undoubtedly would have seen the play. This Sienese play is the basis for Twelfth Night.