Cymbeline, the Roman Empire's vassal king of Britain, once had two sons, Guiderius and Arvirargus, but they were stolen twenty years earlier as infants by an exiled traitor named Belarius. Cymbeline discovers that his only child left, his daughter Imogen (or Innogen), has secretly married her lover Posthumus Leonatus, a member of Cymbeline's court. The lovers have exchanged jewellery as tokens: Imogen with a bracelet, and Posthumus with a ring. Cymbeline dismisses the marriage and banishes Posthumus since Imogen — as Cymbeline's only child — must produce a fully royal-blooded heir to succeed to the British throne. In the meantime, Cymbeline's Queen is conspiring to have Cloten (her cloddish and arrogant son by an earlier marriage) married to Imogen to secure her bloodline. The Queen is also plotting to murder both Imogen and Cymbeline, procuring what she believes to be deadly poison from the court doctor. The doctor, Cornelius, is suspicious and switches the poison with a harmless sleeping potion. The Queen passes the "poison" along to Pisanio, Posthumus and Imogen's loving servant — the latter is led to believe it is a medicinal drug. No longer able to be with her banished Posthumus, Imogen secludes herself in her chambers, away from Cloten's aggressive advances.
