Verdigris deep - Frances Hardinge

Verdigris n. a blue-green rust that tarnishes ageing and forgotten copper coins, altering them entirely . . .

When Ryan and his friends are caught stranded and penniless late one night, they steal some coins from a well for their bus fare home. Soon after, strange things begin to happen. Peculiar marks tingle on Ryan's knuckles, light bulbs mysteriously explode and a terrified Chelle starts speaking words that aren't her own.

Then the well witch appears, with her fountains for eyes and gargled demands. From now on, the friends must serve her . . . and the wishes that lie rotting at the bottom of her well.

In the tradition of truly fantastic storytelling, VERDIGRIS DEEP is darkly witty, utterly unexpected and shiver-down-the-spine sinister