A summer of drowning

A young girl, Liv, lives with her mother on a remote island in the Arctic Circle. Her only friend is an old man who beguiles her with tales of trolls, mermaids, and the huldra, a wild spirit who appears as an irresistably beautiful girl, to tempt young men to danger and death. Then two boys drown within weeks of each other under mysterious circumstances, in the still, moonlit waters off the shores of Liv's home. Were the deaths accidental or were the boys lured to their doom by a malevolent spirit?