THE Argument briefly summarises the plot.

Act I. A Field of Battle on the Banks of Hydaspes, with [overturned tents and chariots, soldiers, scattered arms, banners and other] Remains of Porus's Army, defeated by Alexander. Poro and his general Gandarte with their Swords drawn. Poro after a vain attempt to rally his troops offers to kill himself. Gandarte stops him, and seeing soldiers at a distance urges flight and takes off his helmet. On his suggestion they exchange their Helmets. Timagene, Alessandro's general and favourite, enters with his Sword drawn and attended by Macedonians. Poro endeavouring to defend himself, drops his Sword. Alessandro enters and sends Timagene away. Poro, recognising Alessandro, gives his name as Asbite. Alessandro, claiming to be fired not by ambition but by the search for virtue equal to his own, enquires about Poro. On hearing of his worth as King and warrior, he sends ‘Asbite’ to him: let Poro confess that Alessandro has defeated him and then return in peace to his Kingdom. Offering ‘this precious Spoil of great Darius’, he takes a Sword from his own Side and gives it to Porus, a Soldier presenting another to Alexander. Poro says it will deal destruction on the donor and departs. Timagene brings in Poro's sister Erissena in Chains; two Indians and a Retinue of Grecians. Alessandro rebukes the Indians for trying to gain his favour by chaining a woman and orders them to be fettered and dragged to Poro. He frees Erissena: he did not come to India to subdue ‘defenceless Damsels’. She is surprised to find Greeks so mild. Timagene offers her his love, remarking aside that Alessandro killed his father. She replies that she loves no one. The set changes to An Inclosure form’d by Palm and Cypress Trees [with a small temple dedicated to Bacchus] in the Palace of Cleofida. She sends her Attendants to look for Poro; he enters and tells her bitterly that Alessandro is victorious and will soon lay his trophies at her feet. She rebukes him for jealousy: she is pretending in order to save him (Poro). When, going, she threatens to ‘abandon this detested climate’, he promises to forget his suspicions. She makes him swear it by the sacred God of India.