Cymbeline, a tragicomedy by William Shakespeare, is one the Bard's more obscure plays. Borrowed, barely, from Celtic lore, it tells the story of a king who rebels against Rome because of his evil wife. For unrelated reasons, his daughter spends most of the play cross-dressing and looking for her banished husband. Actually, it's more about the latter than the former.
Cymbeline is king of a city in Britain, during the time of The Roman Empire. His daughter, Imogen, is in love with Posthumus, a poor nobleman. They marry, which infuriates Cymbeline, and so he banishes Posthumus to Italy. In Italy, Posthumus meets Jachimo (or Iachimo), who makes a bet. He says he can seduce Imogen, and prove that all women are naturally unfaithful. Jachimo goes to Britain, but failing to seduce Imogen by traditional means, resorts to trickery. Hiding himself in a chest in her room, he watches her sleep and collects details from her room. He also steals a bracelet, which was a gift from Posthumus.
Jachimo returns to Italy, hands Posthumus the bracelet, and provides details on Imogen's room and her naked body. Posthumus sends word to his servant Pisanio in Britian to kill his wife for her infidelity. Pisanio does not believe Imogen has cheated, so he convinces her to disguise herself as a boy and find her husband, so she can tell him her side of the story; Pisanio, meanwhile, will tell Posthumus she's dead. Imogen goes off to find her husband, but gets lost in Wales; she meets an exiled nobleman and his two sons. Unbeknownst to them but knownst to the nobleman, they are actually Cymbeline's sons (and Imogen's brothers); the nobleman kidnapped them in revenge for being exiled.
We learn that Cymebline's Queen has convinced him to stop paying tribute to Rome, so Rome is about to attack. Due to circumstances,  Imogen believes Posthumus is dead, and Posthumus regrets murdering her; she mourns, and he tries to kill himself by first fighting for Britain against Rome, then switching into Roman garb when the Britons win. Jupiter, the god, shows up to say he'll protect Posthumus. The next day, Posthumus is brought out as a prisoner, and one by one the cast shows up to explain the plot. Everyone lives happily ever after, except the Queen, who dies; with her dead, Cymbeline decides to start paying tribute to Rome again.
Basically, the play is a mishmash of plots Shakespeare regularly used in other plays. One interesting aspect of it, though, is that the characters can be read as allusions to Jacobean figures. James of England is Cymbeline; his goal of unity and peace is upset by the warmongering Queen (Elizabeth I). When the Queen dies, peace resumes. The play also emphasizes the concept of "Britain" -- the word appears more in this play than any other Shakespeare play, while the word "England" appears not a once; James was a big pusher of British unity.
- Anachronism Stew: Among other things, while the play is set in Roman times during the reign of Claudius, Iachimo is pretty much a (stock evil) Renaissance Italian and his scenes with Postumus feel "contemporary" (for the time of Shakespeare).
- Ancient Rome: Where we lay our scene.
- And Another Thing: The entire last act of the show. In the space of a few dozen lines, Iachimo's treachery is revealed, Posthumous reveals who he is and claims to have killed Imogen, Imogen reveals who she is and that she is alive, the Queen is revealed to have been behind everything, Guiderius admits to having killed Cloten, and the princes are revealed to be royalty.
Cymbeline: New matter still?
- Ask a Stupid Question: Immediately after one of the banished princes decapitates Cloten, their caretaker roars "What has thou done?" The response: "Cut off one Cloten's head."
- Berserk Button: Posthumus is so convinced of Imogen's purity that he goes straight into a berserk rage vowing to "tear her limbmeal" when he's convinced she's cheated on him.
- Cruel Mercy: Posthumous to Iachimo after The Reveal:
"Kneel not to me
- Expy: Iachimo essentially means "little Iago"; some have argued he's supposed to be a toned-down version of Othello's infamous villain.
- Faux Death
- Fidelity Test: Imogen passes, but Posthumus thinks she doesn't.
- Friendly Enemies: Cymbeline and Lucius
- Genre Savvy: Posthumus' friends and Pisanio easily deduce Imogen's supposed infidelity is Not What It Looks Like.
- God Save Us From the Queen
- Wicked Stepmother: Lampshaded in that one of the Queen's first lines is declaring that she is not like the wicked stepmothers of the tales. She totally is.
- Honor Before Reason
- Incest Is Relative: The Queen convinces Cymbeline to join her in persuading Imogen to marry her step-brother Cloten.
- Ineffectual Sympathetic Villain: Iachimo, which is part of why he gets reprieved. Notably, in the Boccaccio story the play is based on, the equivalent character is covered in honey and put in a cage and gets stung to death by insects. In particular, the whole "hiding in the chest" idea is vaguely ridiculous, making him a literal Jack-in-the-box, as is the Peeping Tom aspect, even though his reason for doing so isn't funny.
- It doesn't hurt that he's shown as remorseful when he realizes that his actions might have caused Imogen's death. His motivation for the deception lies somewhere between For the Lulz and For The Money.
- In the Blood: The exiled princes, Caius Lucius, and Cymbeline all echo the sentiment of Imogen's essential noble nature when they meet her disguised as Fidele.
- It Was a Gift
- Lampshade Hanging: The Queen tells Imogen she's not a Wicked Stepmother (she's lying, of course).
- Laughably Evil: Cloten is amusing in a stupid thug kind of way. Even when yelling about how he will rape his sister while wearing her lover's clothes to prove he's more worthy of her.
- Mistaken for Cheating: As stated by Posthumus in one of his ranting monologues, it's made worse by the fact that Imogen had consistently refused to sleep with him.
"Me of my lawful pleasures she restrained / And prayed me oft forbearance"
- My God, What Have I Done?: Posthumus after he thinks he's successfully orchestrated Imogen's murder.
- Not What It Looks Like
- Parental Marriage Veto
- Poor Man's Substitute: As noted above, people tend to see the characters as inferior versions of Shakespearean characters/types developed more deeply in other plays: Iachimo - Iago; Postumus - Othello; the Queen - someone like Lady Macbeth or Goneril and Regan; Cymbeline - King Lear; Imogen - your standard crossdressing heroine. On the other hand, you really do get a bunch of Shakespearean plays for the price of one.
- Post Modernism: "Shall's have a play of this?"
- Rags to Royalty
- Secondary Character Title
- Sweet Polly Oliver
- Those Two Guys: The creatively named First Lord and Second Lord who exist to explain the prologue and to play the Straight Man to The Clown Cloten. Productions frequently have the same two actors play First and Second Soldier, and First and Second Jailer who have similar parts.
- Two Lines, No Waiting
- Wrongful Accusation Insurance
- The Queen, who is evil, gives Imogen a potion that is supposed to be poison but Imogen thinks it's medicine but it turns out to just be a sleeping potion; while she's sleeping, Imogen's brothers kill the Queen's son, who has the hots for Imogen and was out looking for her, and when she wakes up she thinks he's Posthumus. Whew!