I can't believe I haven't finished hallucina...I mean, "Melusine" yet.

"Ghosts beneath our feet : Wright, Betty Ren"

https://archive.org/details/ghostsbeneathour00wrig

"Melusine : Lynne Reid Banks": Free Download, Borrow, and Streaming : Internet Archive

https://archive.org/details/melusinemystery00bank_0