Most famously the young hero stole aboard one of the Minoan raiding ships along with a handful of his most trusted and bravest guards. The ships and the Athenian captives on board were bound for the palace of Knossos and the Labyrinth beneath. Set loose, the captives are destined to be devoured by the Minotaur that reside there.
On discovering who was aboard one of the ships, Minos, the King of Crete made boasts that Theseus's death would be a sacrifice great enough sate the gods and return power to the Minoan people. Ariadne, daughter of King Minos pitied Theseus and his men and sought to aid them.
Ariadne organised for a cache of weapons in the Labyrinth to be left where Theseus and his men would stumble upon them and arranged for for the secret routes through the maze to be imparted to Theseus to ensure that he could escape.
King Minos enraged by Ariadne's treachery ordered her to be thrown into the Labyrinth alongside Theseus and his men. Surrounded by rough walls, flickering torches and the screams of other captured souls the party set out to rescue the other captives, avenge the fallen and escape to freedom.
The Labyrinth beneath Knossos was not of ordinary construction, the inventor Daedalus had crafted it with mechanical contraptions which endlessly shift the walls. It was both a prison for the Minotaur and an endless puzzle for those thrust inside. The longer and further into the maze one wandered the more lost and confused they would become.
Legend says that on that day Theseus single-handedly slew the great Minotaur Asterios, the first of his kind, escaping with his loyal soldiers, a number of other victims and the beautiful Ariadne from the Labyrinth to a waiting Athenian Ship.