At Cymbeline's palace, the Queen is giving instructions to pick flowers while the dew is on the ground. Then she asks the doctor, Cornelius, whether he has brought the drugs. He presents a box to her, but his conscience prompts him to ask why she requires these slow but deadly poisons. Annoyed at being questioned, she replies that while the doctor has trained her in the herbal arts of distilling and making perfumes, she wants to extend her skill by testing these compounds on non-human subjects - by implication, animals. Cornelius is not impressed, and points out that she will only harden her heart.
The Queen ends the conversation abruptly and Pisanio enters. In an aside, the Queen reveals her intention to try her poisons first on him, as he is on Posthumus's side and an "enemy" to her son in the question of Imogen. As she dismisses Cornelius, he remarks in an aside that he knows of her malice, and will ensure that she does no harm. The drugs he has given her are not the deadly poisons she requested, but potions to "stupefy and dull the sense awhile." She will try them on cats and dogs, and later humans, but the effect will be merely to lock up the spirits temporarily, only for the subject to awaken refreshed.
The Queen hopes Imogen's affections for Posthumus will cool. She promises Pisanio that when he brings her word that Imogen loves Cloten, she will make him as great as his master, Posthumus. In fact, he will be greater, as Posthumus cannot return; neither can Posthumus provide for Pisanio.
The Queen then drops the box, and Pisanio picks it up. The Queen urges him to take it as a token of further favors she intends to him, claiming she has five times saved the King's life with its contents. She orders Pisanio to tell Imogen what she must do (presumably, to renounce Posthumus and marry Cloten). She reminds him that if he brings about her desire, he will still have his mistress, Imogen, and Cloten also to give him preferment. In addition, she will persuade the King to grant whatever he wishes, and she herself will be obligated to reward him.
Pisanio leaves without responding, and the Queen reveals that she mistrusts him, as she believes he is still loyal to Posthumus and Imogen. She says if he takes what she believes to be poison, Imogen will have no supporters. If Imogen continues to defy the Queen, she too will be given poison, leaving Cloten as heir to Cymbeline's throne. Pisanio re-enters to reveal to the audience that he would rather choke himself than prove untrue to Posthumus.
The Queen's instructions to pick flowers while the dew is on the ground has sinister significance. Belarius, at Act 4, scene 2, lines 284-5, comments that "The herbs that have on them cold dew o'th'night / Are strewings fitt'st for graves." Herbalists advised that medicinal herbs should be picked when dried by the sun, since dewy herbs would rot quickly and would therefore be less wholesome and unsuitable for healing. The Queen, obsessed with poisoning people who stand in her way, wants to put the flowers to an evil use, which stands in contrast to the life-affirming floral imagery surrounding the young lovers. This is part of the play's theme of the regenerative role of the younger generation contrasted with the destructive and decaying role of the older generation.
The theme of appearance versus reality is presented with a twist in the doctor's determination to be true to mankind in general by being false with the Queen: by his lie about the effects of the herbs he has given her, he will save her intended victims from poison.
The Queen's treachery and deceit is contrasted with the loyalty and integrity of Pisanio and Cornelius.
Cymbeline: Novel Summary: Act 1 Scene 6