Charybdis (a whirpool) and Scylla (a multi-headed monster) was the same episode in Homer's Odyssey. That was the whole point of the episode: Ulysses had to decide whether to risk his entire ship and crew or definitely sacrificing a few for guaranteed passage of the rest. The classic trolley dilemma for an audience of bronze-age seafarers.
Or perhaps I read a completely different "Odyssey" by a different "Homer"?