Helenka Stachera Libri

Fin is a foundling growing up in the Hackney marshes in Victorian London, living in a tiny attic and selling leeches for a living. When she accidentally discovers she is the lost-lost child of a rich Polish family called the Kaminskis, she is swept up into a supernatural adventure where she has to use everything she has learned on the streets of London and deep in the marshes to stay alive. For the Kaminskis are haunted by an ancient evil - and Fin is the key to stopping it forever . . .

When Bela's mother dies, she is summoned to deepest Siberia to stay with an uncle she's never met. Exploring his strange scientific workshop, she uncovers a secret she was never meant to find - a doorway that opens an to icy land, frozen in time and full of legends come to life. But this frozen land is in danger, and it's up to Bela to find a way to save it. To succeed, she must join forces with the a long-lost sister she never knew she had, born 40,000 years before . . .