Ice twins. S. K. Tremayne. 2015.

After one of their identical twin daughters, Lydia, dies in an accident, Angus and Sarah Moorcroft move to a remote Scottish island, hoping to mend their shattered lives. But when. Their surviving child, Kirstie, claims they have mistaken her identity - that she, in fact, is Lydia - their world comes crashing back down.

They know one of their daughters died. But can they be sure which one?