Mirrorland is a childhood fantasy room where Scottish twins Ellice and Catriona, or El and Cat, spend most of their time. It's populated by odd and sometimes disturbing companions, who are more imaginary tormentors than friends. Joining the dysfunctional fray is Ross, the boy next door, who becomes so enmeshed in the twins' world that in the present-day portion of the narrative, he's married to El, who is now missing. Only Cat believes her sister is alive, and, as the pages turn and the past and present and the real and liminal alternate, readers will become as enmeshed as Ross while the girls' two lives--one in the house (a portion of the story that's overly long), the other after they run away--unspool to devastation. Beware: sexual and coercive abuse abound here. But there's more to the book than psychological voyeurism. Johnstone's twisting debut novel stands alone as one to notice, and it's a must for fans of unreliable narrators.

Cat Morgan, the narrator of Johnstone's intriguing if uneven debut, fled Scotland years ago and settled in Los Angeles. When she gets a call from Ross MacAuley, her brother-in-law, informing her that her estranged twin sister, Ellice MacAuley, has gone missing while sailing on the Firth of Forth, she returns home to Edinburgh. Cat stays at the house where she and El grew up and shared an imaginary world they called Mirrorland, a place where they could escape the grim realities of their childhood, which included physical and emotional abuse. Cat decides she must immerse herself once more in Mirrorland if she's to solve the mystery of El's disappearance. Cat's quest is complicated by her belief that El is not dead, her receipt of anonymous notes warning her to leave, and the rekindling of her complex relationship with Ross. Johnstone skillfully juxtaposes Mirrorland against the real world, but El is seen only through Cat's unreliable eyes, and their relationship is so confused that the reader may wonder how much of what Cat says about El is true. This ambitious blend of psychological suspense and horror casts a powerful light on the liberating power of imagination. Agent: Allison Hunter; Janklow & Nesbit Assoc. (Apr.)

When her identical twin sister goes missing, a Scottish writer living in Los Angeles returns home. On Sept. 5, 1998, identical twins Ellice and Catriona show up at Edinburgh's Granton Harbour at dawn, covered in blood and badly beaten, seeking passage aboard a pirate ship. That was the day their second life began. Fast-forward almost two decades and the now 31-year-old twins are estranged. El is married to their childhood friend Ross and living in Edinburgh in the house on Westeryk Road where the twins had lived with their mother and grandfather. Cat is single and living in a condo overlooking the Pacific Ocean in Southern California. When El goes missing while sailing, Ross calls Cat, and she rushes back to Edinburgh. Cat is convinced that El is fine because she has an unshakable belief that she would have felt it if her sister were dead, and the cruelty of going missing is exactly what she would expect from El. Returning to her childhood home stirs up long-buried memories for Cat. Front and center among those are the endless hours the pair spent with Ross and a host of imaginary friends in Mirrorland, their name for the secret covered alley next to the house that was the setting for their childhood adventures on the high seas, in the Wild West, and at the prison from TheShawshank Redemption. Author Johnstone has created a dark, twisting thriller that explores the pitch-black corners of people's minds; how good and bad, love and hate, terror and joy can co-exist; and how childhood memories can be rewritten with time as the lines between imagination and reality are blurred. Fans of Gillian Flynn's creeping dread and Liane Moriarty's nuanced morality and complex relationships should love this book. An enthralling thriller. Copyright (c) Kirkus Reviews, used with permission.