The Considine Curse

Mariel doesn't know that she has long lost cosins and aunts and uncles.  There is a wierd thing about the Consodine family because every night Mariel (the normal cosin) wakes up and finds a bed empty and a window flung open.

Will Mariel ever discover the great mystery about the Consodine?

I would recommend this book for children from 9-14.