The work belongs to a series of eight mythology themed oval plaquettes by Guglielmo della Porta. In Greek mythology, the hero Perseus was known for slaying Medusa, a gorgon with snake hair whose grotesque appearance turned people to stone. The relief depicts a later episode in the hero's life. The wedding of Perseus and Andromeda was interrupted by a warlike crowd led by Phineus, a disappointed suitor. After a fierce battle, Perseus finally won, turning his opponents to stone with Medusa's head. The artwork is a dynamic multi-figure composition with Perseus in the centre – a warrior in a helmet with a sword in his right hand lowered to the ground and Medusa’s head in his outstretched left hand. On the right are the bodies of enemies killed by the monster's gaze. In the background, against the backdrop of an architectural arch, the battle between Perseus' companions and Phineus' warriors continues. On the left, at the table, sits Andromeda's father, King Cepheus of Ethiopia, in whose palace the wedding is taking place, and to his right is his wife, Cassiopeia.