A brief introduction mentions the fall of Adam and Eve caused by the serpent, which was Satan, who led the angels in revolt against God and was cast into hell. The scene then opens on Satan lying dazed in the burning lake, with Beelzebub, next in command, beside him. Satan assembles his fallen legions on the shore, where he revives their spirits by his speech. They set to building a palace, called Pandemonium. There the high ranking angels assemble in council.
A debate is held whether or not to attempt recovery of heaven. A third proposal is preferred, concerning an ancient prophecy of another world which was to be created, where the devils may seek to enact their revenge. Satan alone undertakes the voyage to find this world. He encounters Sin and Death, his offspring, guarding hell's gates. Sin unlocks the gate, and Satan embarks on his passage across the great gulf of chaos between heaven and hell, till he sights the new universe floating near the larger globe, which is heaven.
God sees Satan flying towards this world and foretells the success of his evil mission to tempt man. God explains his purpose of grace and mercy toward man, but declares that justice must be met nonetheless. His Son, who sits at his right hand, freely offers to sacrifice himself for man's salvation, causing the angels to celebrate in songs of praise.
Meanwhile Satan alights upon the outer shell of the new creation, where he finds an opening to the universe within. He flies down to the sun, upon which an angel, Uriel, stands guard. Diguised as a cherub, Satan pretends he has come to praise God's new creation, and thereby tricks the angel into showing him the way to man's home.
Landing atop Mt. Niphates, Satan experiences dissillusionment, but soon proceeds on his evil errand. He easily gains secret entrance to the Garden of Paradise. He wonders at its beauty, and soon comes upon Adam and Eve, who excite great envy in him at their happy state. He overhears them speak of God's commandment that they should not eat the fruit of the Tree of Knowledge of Good and Evil under penalty of death, and thereby plots to cause them to transgress.
Uriel, becoming suspicious, comes to warn Gabriel and his angels, who are guarding the gate of Paradise. That evening, two scouts sent by Gabriel find Satan whispering in the ear of Eve as she sleeps next to her husband. The scouts apprehend and bring Satan to Gabriel who banishes him from Eden.
Next morning, Eve relates to Adam a troublesome dream, and is comforted by him. God sends the angel Raphael to visit the couple to warn them of their enemy. The angel arrives and dines with them, then relates to them the history of Satan's fall: how jealousy against the Son of God led him to incite all those in his charge to rebel against God, and how one angel, Abdiel, resisted and remained faithful to God.
Raphael continues to relate how Michael was sent to lead the faithful angels into battle against Satan (then called Lucifer) and his army. Wounded and in dissaray, Satan and his powers retreat. During the night they invent weapons resembling cannons. When, in the second day's fight, Michael's angels are confronted with these devilish devices, they become enraged and pull up the very mountains and hurl them at Satan's crew. But the war continues into the third day, when God sends Messiah, his Son, to end the war. Riding forth in his flaming chariot, Messiah drives the rebels out of heaven and down into hell.
Raphael then relates to Adam how God sent his Son to create a new world and new creatures to fill the place left by the fallen angels. The six days of creation are described.
Adam, desiring to extend the pleasurable visit with the angel, relates to Raphael what he remembers of his own creation, his first impressions of the world and its creatures, the Garden of Eden, and his first meeting and marriage to Eve. After repeating his warnings to Adam, the angel departs.
Satan returns to earth, where he chooses the serpent as his best disguise. Next morning, when Adam and Eve go forth to their gardening tasks, Eve suggests they go in separate directions. With great reservation, Adam finally consents. The serpent finds Eve alone and approaches her. She is surprised to find the creature can speak, and is soon induced by him to eat the fruit of the forbidden tree. Adam is horrified when he finds what she has done, but at length resignes himself to share her fate rather than be left without her, and eats the fruit also. After eating, they are aroused with lust and lay together, then fall to restless sleep. They waken to awareness of their nakedness and shame, and cover themselves with leaves. In their emotional distress, they fall into mutual accusations and blame.
The guardian angels return to heaven, sad for man's failure, and the Son of God descends to earth to judge the sinners. Mercifully, he delays their sentence of death many days, during which they may work to regain God's favor. Then, in pity, he clothes them both.
At the gates of hell, Sin and Death sense the success of Satan in this new world. They set out to build a highway over chaos to make future passage to earth easier. Satan meets them on his return voyage to hell, and marvels at the great structure. Upon his arrival in Pandemonium, Satan boasts of his success to the assembly. Instead of applauding him, they can only hiss, for they and he have all been turned into snakes, their punishment from above.
God instructs his angels what changed conditions must prevail in the world, now in fallen state, while on earth, Adam bemoans his miserable condition and the fate of the human race. He harshly rejects Eve's attempt to console him, but she persists and wins his forgiveness. She proposes they commit suicide, but Adam reminds her of God's promise that her seed should wreak vengeance upon the serpent. Moreover, they must seek to make peace with their offended Lord.
God sends Michael and his band to expel the sinning pair from Paradise, but first to reveal to Adam future events, resulting from his sin. The angel descends to Eden with the news of their expulsion, causing Eve to withdraw in tears. Michael leads Adam up a high hill, where he sets before him in visions what shall happen till the Great Flood.
Michael continues in prophecy from the flood by degrees to explain who the Seed of woman shall be, the Savior which was promised, who shall redeem mankind. Adam is recomforted by these last revelations and resolves faithful obedience. He descends the hill with Michael and rejoins Eve, who is wakened from gentle sleep, reconfirmed in allegence to her husband. A flaming sword is placed to bar the gates behind them, as Adam and Eve are sent away from Paradise.