家族成員各個個性古怪且互相討厭的DARKER一族，為了幫堅信自己快去世的老奶奶過生日，在偏遠的小島Seaglass上聚集，Daisy Darker卻越來愈越感到害怕，認為祖母的預言會成真，而當眾人發現祖母真的去世，以及一首刻寫在廚房牆上的詭異短詩，究竟是否真有外人入侵島上？抑或是內賊故弄玄虛？ Daisy Darker's family were as dark as dark can be, when one of them died all of them lied and pretended not to see . . . Daisy Darker is arriving at her grandmother's house for her eightieth birthday. It is Halloween, and Seaglass - the crumbling Cornish house perched upon its own tiny private island - is at one with the granite rocks it sits on. The Darker family haven't all been in the same place for over a decade, and when the tide comes in they'll be cut off from the rest of the world for eight hours. When the tide goes back out, nothing will ever be the same again, because one of them is a killer . . .