Ino was a mortal queen in Greek mythology, second wife of Athamus and mother of Learches and Melicertes, daughter of Cadmus and Harmonia and stepmother of Phrixus and Helle.
Phrixus and Helle, twin children of Athamus and Nephele, were hated by their stepmother, Ino. Ino hatched a devious plot to get rid of the twins, roasting all the towns crop seeds so they would not grow. The local farmers, frightened of famine, asked a nearby oracle for assistance. Ino bribed the men sent to the oracle to lie and tell the others that the oracle required the sacrifice of Phrixus. Athamus reluctantly agreed. Before he was killed though, Phrixus and Helle were rescued by a flying golden ram sent by Nephele, their natural mother. Helle fell off the ram into the Hellespont (whch was named after her) and died, but Phrixus survived all the way to Colchis, where King Aeetes took him in and treated him kindly, giving Phrixus his daughter, Chalciope, in marriage. In gratitude, Phrixus gave the king the golden fleece of the ram, which Aeetes hung in a tree in his kingdom.
Later, Ino raised Dionysus, her nephew, son of her sister Semele, causing Hera's intense jealousy. In vengeance, Hera struck Athamus with insanity. Athamas went mad, and slew one of his sons, Learchus, thinking he was a ram; Ino, to escape the pursuit of her frenzied husband, threw herself into the sea with her son Melicertes. Both were afterwards worshipped as marine divinities, Ino as Leucothea ("the white goddess"), Melicertes as Palaemon. Alternatively, Ino was also stricken with insanity and killed Melicertes by boiling him in a cauldron, then took the cauldron and jumped into the sea with it. A sympathetic Zeus didn't want Ino die, grateful for having raised his son Dionysus, and turned her and Melicertes into Leucothea and Palaemon, respectively.
The story of Ino, Athamus and Melicertes is relevant also in the context of two larger themes. Ino, daughter of Cadmus and Harmonia, had an end just as tragic as her siblings: Semele died while pregnant with Zeus' child, killed by her own pride and lack of trust in her lover; Agave killed her own son, King Pentheus while struck with Dionysian madness and Actaeon, son of Autonoe, the third sibling, was torn apart by his own hunting dogs. Also, the insanity of Ino and Athamus can be explained as a result of their contact with Dionysus, whose presence can cause insanity. None can escape the powers of Dionysus, the god of wine.
When Athamus returned to his second wife, Ino, Themisto (his third wife) sought revenge by dressing her children in white clothing and Ino's in black. Ino switched their clothes with Themisto knowing and she killed her own children.