The play opens in a chamber of Philaster’s palace. Dion, Claremont and Thrasiline, his loyal noblemen, are talking about the current situation of Sicily (where the plot is laid). It is revealed by their discussion that King of Calabria has usurped the rule of Sicily from the father of Philaster (now dead).
But as Philaster is very popular among the people of Sicily, the new king could not kill him and has to keep him alive and give him all the comforts and freedom.
The new king is supposed to marry his daughter, Arethusa to Pharamond (a Spanish Prince) who, after marriage will become the new ruler of Sicily.
Thrasiline talks about the rumour that the lady namely Megra, who had gone to welcome him got some interest in Pharamond and “there is too close an intercourse between him and lady.”
Meanwhile, the new king along with Pharamond, Arethusa and other nobles enter the palace. King announces that he will marry his daughter to Pharamond and also make the later his successor.
At this Pharamond declares his love for Arethusa and says, “My reign shall be so easy to the subject, that every man shall be his Prince himself, and his own law”. Philaster enters.
Calling Pharamond a “foreign man”, he declares “when thou are king, look, I be dead and rotten, and my name ashes.” King calls him to be too bold to speak so.
At this Philaster calls himself “a faint shadow that every drunken cloud fails over.” After the argument, the king and his party go away angrily. Claremont and Dion express their loyalty to Philaster, which pleases him.
Arethusa invites Philaster to her private chamber where both express their love for each other. Philaster tells her that he will send his loyal page (a servant) to convey his secret messages to her.
Pharamond enters and scolds Philaster for being in the chamber of Arethusa. Both argue. Philaster goes away. Pharamond persuades Arethusa to spend a night with him but Arethusa cleverly refuses and goes away. Pharamond becomes doubtful about Philaster and Arethusa and declares to take revenge from Philaster.
Philaster faces difficulty in making Bellario (his page) go to Arethusa as his secret messenger who refuses but agrees at last. Meanwhile, Galatea (an attendant) tells Arethusa about the affair of Pharamond and Megra.
Bellario enters and both introduce each other. Arethusa is quite astonished by the devoutness of Bellario to Philaster.
In another chamber of the palace, Megra and Pharamond argue as they have committed adultery and are exposed. Megra, in order to save herself, spreads the rumor that Arethusa has a handsome servant and there is some affair between the two.
Pharamond, hearing this, angrily says, “I’ll disgrace her first, then leave her to shame.” King enters and seeing Megra scolds her for sleeping with Pharamond.
Megra says to the king, “Your daughter, Arethusa, the glory of you Sicily, which I, a stranger to your kingdom, laugh to scorn, I know her shame, and will discover all: Nay, will dishonor her. I know the boy she keeps, a handsome boy, about eighteen; Know what she does with him, and where, and when.”
Saying so, she goes away. King is quite confused.
Philaster also hears the rumours of this affair but does not believe and tries to find out the truth. Bellario enters. Philaster inquires about Arethusa. Bellario, unaware of the intentions of Prince tells him how lovingly Arethusa kept him.
Philaster now believes that rumours were true and accuses Bellario of having affair with Arethusa. Bellario protests but Prince does not believe him. Bellario being helpless runs away.
Meanwhile, the new king approaches her daughter, Arethusa and blames accusing her orders her to put Bellario away. Being angry, he says, “You are the one shame with me” and goes away.
Arethusa sighs, “Where may a maiden live securely free, keeping her honour safe.” A little later, Philaster comes and inquiring about Bellario accuses her of the same cause. Calling her double-faced he desires to run away from womanhood and exits.
Bellario enters and Arethusa pleads him to run away. Bellario says, “This grief you add unto me is no more than drops to seas for which they are not seen to swell” and tells her he has been already scolded by Prince and going to depart.
Both bid farewell to each other. A lady enters and tells Arethusa that king has called her to go hunting with him. Arethusa says, “I am in tune to hunt.”
Act 4 of the play is laid in the forest. Philaster alone in the woods mourns for being deceived and blames womanhood. Bellario, who is also in the forest happens to see him and offers his pity. Philaster being enraged asks him to go away.
Bellario, with great sorrow, goes away. Meanwhile, Arethusa, who has come for hunting, runs away. The king’s men search for her. Arethusa on her flight prays, “Heaven, I hope, will ease me. I am sick.” Bellario comes to her. She faints and he tries to wake her up.
A little later, she comes back to her senses. Just then, enters Philaster. Seeing both again together, his rage knows no bounds. He tries to kill Arethusa with his sword, but a countryman rushes and prevents him from doing so.
A fight starts between them. Philaster is wounded. King’s men, while searching for Arethusa, reach near to their location. Philaster and Bellario run away.
Pharamond asks about the identity of the person who wounded Arethusa, but she makes some excuses and does not reveal his identity.
Countryman tells them that the person who tried to kill Arethusa has run away but is wounded and would not have gone far. They start searching for Philaster. In another part of the forest, Bellario whom Philaster has wounded during their flight cries of pain and goes to sleep.
Philaster comes and scolds him again. Thumping sound is heard. Ballario makes Philaster run away. At this Philaster is assured of the innocence of Bellario and Arethusa.
Pharamond, with his men, arrive. Bellario takes all the charges and confesses that he has harmed Princess. Philaster comes out of his hide. Both of them take charge of themselves.
King arrives. It is declared that Philaster is assailant. Arethusa requests her father to hand over the culprits to her. King grants her request. All exit.
Philaster repents for doing wrong with Arethusa and Bellario. They try to calm him down but he weeps over his past deeds. The king orders his execution. A messenger arrives and informs the king that Pharamond has been captured by the mob (that supports Philaster).
Other messengers also arrive and tell the king that the mob is out of control now. King at once rushes to Philaster. He gives him both his daughter and throne and requests him to calm down the angry mob.
Philaster agrees and succeeds in cooling down the mutiny and also freeing Pharamond from them. Pharamond decides to return back to Spain. Philaster suggests that Megra should accompany him on her voyage.
Megra feels offended and declares that Bellario should be punished. Philaster prays for his (Bellario) life. King thus orders to torture him by taking his clothes off. Bellario reveals that he is not male. She is actually the daughter of Lord Dion (the noble).
Her father would often narrate the stories of Philaster’s chivalry and gradually she fell in love with him. Being aware of her status and gender, she disguised herself as a boy so as to remain close to Philaster.
All praise her deep love. King bids farewell to Pharamond and also congratulates and blesses Philaster.