In Greek mythology, Hypermnestra was a Libyan princess by birth and queen of Argos by marriage — daughter of Danaus, one of the fifty Danaids, and the only sister who refused her father's order to murder her husband on the wedding night. She spared Lynceus, was tried and acquitted (or saved by Aphrodite), and with him founded the Abantiad line through their son Abas.
Adapted from Wikipedia, "Hypermnestra" · CC BY-SA 4.0
I.Family
Hypermnestra is daughter of Danaus; Apollodorus makes her and Gorgophone the two daughters by Elephantis, the other Danaids having different mothers. Other notices give Melia, daughter of Agenor, as mother of all fifty. She marries her cousin Lynceus, son of Aegyptus, and bears Abas, eponymous founder of the Abantiads and of Abae.
She is distinct from any lesser homonyms; this entry is the merciful Danaid only.
II.The wedding night
Fleeing Aegyptus' demand that his fifty sons marry Danaus' fifty daughters — and an oracle that a son-in-law would kill him — Danaus settled at Argos. Under siege he consented to a mass wedding but armed the Danaids to kill their husbands in sleep. Forty-nine obeyed; Hypermnestra alone refused — because Lynceus honored her wish to remain a virgin, or, in Ovid's Heroides, because she judged murder barbarous.
She helped him flee to Egypt or to Lynceia in the Argolid; signal torches between Lynceia and Larissa mark their mutual safety in one local legend.
III.Trial, succession, and afterlife
Danaus imprisoned and tried her; she was acquitted, or Aphrodite saved her, and she dedicated an image of Aphrodite "Bringer of Victory." In some versions Lynceus later kills Danaus; in others Danaus dies and bequeaths the kingdom. The other Danaids are often punished in the underworld with leaky jars; Hypermnestra goes to Elysium.
Ovid's letter, Chaucer's Legend, and several early-modern operas keep her name current.