My Sister Erica — Jane Blackmore

They were the Rhodes sisters, but they looked enough alike to be twins.. Frightened by a cryptic, uncompleted call from Erica, Anna rushed to the memory-filled inn where her sister was staying - only to discover that she had vanished.

The strange assortment of guests all insisted that the flighty, impulsive girl had simply left. Even Simon, the boy she had loved - the man she had never stopped loving - tried to convince her that Erica was in no danger.