London Twist von Barry Eisler

For Delilah, the Mossad’s top seductress, the parameters of the assignment were routine. The contractor: MI6. The objective: infiltrate a terror network, this one operating out of London. The stakes: a series of poison gas attacks on civilian population centers. 

There’s just one wrinkle. The target is a woman–as smart, beautiful, and committed as Delilah herself. And for a cynical operative thrust suddenly out of her element, the twists and turns of the spy game are nowhere near as dangerous as the secrets and desires of the human heart.
*This story is approximately 36,000 words–the equivalent of about 145 paper pages. It is a novella, not a novel.*