All our yesterdays by Cristin Terrill

Bloomsbury, 2013. ISBN 978 14088 35197.
(Age: 15+) Em and Finn suffer terribly from their decision to travel back in time to ensure the destruction of Cassandra, a device originally designed to avert disaster and tragedy.  Altering the sequence of time and the resultant paradoxes which are produced are thought provoking and compelling concepts to construct a story around and this novel had great potential.
Described in split character narratives from the heroine's future and past, the complex alternate realities are difficult to comprehend at times, however this is a feature of the subject and the challenge to the reader is reasonable. An interesting device is used to distinguish the older Em from her younger self which enables the reader to appreciate which aspect is speaking as the complexities and sinister outcomes from Cassandra are revealed.
Clever character and plot developments are features of this story which in its latter stages draws events and relationships together in mind bending parallel histories. Explaining further runs the risk of spoiling the story which hinges on a significant twist which, whilst evident very early, maintains the framework until conclusion.
My criticism of this novel is that whilst the concept is intelligent, the opening chapters are written as if the novel was a later book in a series, relying on a reader's prior knowledge of characters and events. This may be a device to prompt readers to persist, in order to discover what the start was about. It is boldly different to traditional chronological narratives and makes sense when sequences are explained later, however some readers might understandably abandon the novel in frustrated bewilderment.
Strong characters eventually bind this story which sadly loses momentum with the excessive portrayal of teenage social posturing. The characters are not always pleasant as they display flaws and attitudes appropriate to the alternate realities of the time shift. The precocious younger version of Em, a spoiled brat with witless attitudes and juvenile romantic obsessions, later shines as a brave young woman enduring cruelty and torment.
Torture scenes are skilfully implied, effectively conveying fear and prompting revulsion without overt description. Violence is not described excessively but swearing in keeping with the context occurs on a couple of occasions and I would suggest this novel suits 15+.
Rob Welsh