Dawn King 
Ciphers (NHB Modern Plays) [EPUB ebook] 

A smart and provocative thriller about spies, double agents, and the opaqueness of the human soul.
A young woman is found dead. Her sister sets out to find out what happened — and stumbles into a world of secrets and subterfuge that makes her question who Justine really was. How well can you ever know someone who lies for a living?
An Out of Joint, the Bush Theatre and Exeter Northcott Theatre co-production, Ciphers premiered at the Exeter Northcott Theatre in October 2013, directed by Blanche Mc Intyre, before embarking on a UK tour.