ISBN-10: 1556527594
I frowned, and shook my head in a last attempt to clear it. "Are you a witch, then, to know the thing that has not yet come to happen?" And even as I spoke, another thought sprang to my mind. "A witch, or…"
Again she seemed to read my thinking; and she laughed up into my face. "A witch? Are you afraid to wake in the morning on the bare mountain side, and find three lifetimes gone by? Ah, but whatever happens tomorrow, surely tonight is sweet?"
With the speed and liquid grace of a cat, she slip-turned from her kneeling position, and next instant was lying across my thighs, her strange ravaged face turned up to mine and her dark hair flowing over us both. "Are you afraid to hear the music of the Silver Branch? Are you afraid to hear the singing of Rhiannon's Birds that makes men forget?"
I had not noticed the color of her eyes before. They were deeply blue, and veined like the petals of the blue cranesbill flower, the lids faintly stained with purple like the beginning of corruption. "I think you would not need the Birds of Rhiannon to make men forget," I said thickly, and bent towards her.Never fear, it doesn't get any more explicit than that. But ruinous consequences ensue. The woman is Arthur's half-sister, although he doesn't know it at the time.
Here's an interview with author Rosemary Sutcliff, from the excellent Camelot Project at the University of Rochester. Sadly, she spent most of her life in a wheelchair, but by God, the woman could write.