While Hypsipyle talks to the Argives, Opheltes sleeps unwatched. A large serpent sacred to Jupiter grazes the child with its scales and kills him. The Argive princes attack the serpent in order to avenge the child's death; Capaneus succeeds in killing it and thereby incurs the enmity of Jupiter. Opheltes parents, Lycurgus and his wife Eurydice, accuse Hypsipyle of neglecting their son. Keen to protect their saviour, the Argives initiate a commotion at Lycurgus' palace, from which Hypsipyle is saved by her sons Thoas and Euneus who had arrived in search of their lost mother.