Imogen, daughter of the British king Cymbeline, is in love with Posthumus Leonatus, a man raised in her father's court who is possessing exceeding personal merit and martial skill. The two have secretly married, exchanging jewellery as tokens: a ring from Imogen, a bracelet from Posthumus. Cymbeline has discovered the affair and banishes Posthumus for his presumption, for Imogen is currently Cymbeline's only child and so her husband is heir to the British throne. Cymbeline did have two sons before Imogen, Guiderius and Arviragus, but they were stolen twenty years ago as infants by Belarius, a courtier banished as a traitor for supposedly conspiring with the Romans. Cymbeline is a vassal king of Caesar Augustus, and Caius Lucius, a Roman ambassador, is on his way to demand the tribute that Cymbeline, under the influence of his wife the Queen, has stopped paying. The Queen is conspiring to have Cloten, her cloddish and arrogant son by an earlier marriage, married to Imogen. The Queen also is plotting to murder both Imogen and Cymbeline to secure Cloten's kingship, and to that end has procured what she believes to be deadly poison from the court doctor Cornelius; Cornelius, however, suspects the Queen's malice and switches the "poison" with a drug that will cause the imbiber's body to mimic death for a while before reviving. Imogen meanwhile secludes herself in her chambers, resisting entreaties that she come forth and marry Cloten.
