The mythological hero fights against the fearful three-headed dog that guards the Underworld while two figures, possibly the Underworld´s titular gods, Pluto and Proserpina, watch the scene in terror. Rubens was directly inspired by Ovid´s Metamorphoses in his depiction of this test of Hercules, though it is also described in other classical texts, such as Homer´s Iliad and Odyssey. This is one of the most expressive of all the sketches made for the projected decoration of the Torre de la Parada. It was developed on canvas on several occasions by at least three of Rubens´ assistants.