between Scylla and Charybdis

On his long voyage home from Troy, Odysseus had to steer his ship through a narrow strait, and the sailors who knew those waters spoke of it only in whispers. For the channel was guarded on both sides at once, and there was no third way through.

On one cliff lived Scylla — a monster with six long necks and six shrieking heads, each ringed with teeth. She would lean down from her cave as ships passed and snatch sailors straight off the deck, six men at a time, and no one who sailed too near her rock came away whole.

On the other side, hidden beneath the water, lurked Charybdis. Three times a day she swallowed the whole sea down into her throat, dragging ships and men into a roaring black whirlpool, and three times she spat it back up in a chaos of foam. To steer clear of her was to steer straight toward Scylla's waiting jaws.

Odysseus was told the cruel truth plainly: there was no safe course. Hug one shore and the monster took a handful of his crew; hug the other and the whirlpool took them all. He chose to lose six men to Scylla rather than the whole ship to the deep — and sailed on through their screams.

To be between Scylla and Charybdis is to be trapped exactly there: between two dangers so placed that every effort to escape the one drives you closer into the arms of the other.