Outwardly alien arrivals from a distant sea, the lambdas are genetically human. They slip quietly into low-to middle-income jobs and appear to want nothing more than to be left alone. For Cara Gray, they are first a haunting presence in her otherwise ordinary childhood, then the inscrutable target of her police surveillance work. When a bomb goes off at a school, a nebulous group of lambda extremists claims responsibility for the attack — but how could a vulnerable community of tiny aquatic humans, barely visible in society and seemingly indifferent to their own exploitation, be capable of something so horrific? In a world of sentient objects, all-powerful quantum AI, and neuroses-ridden organic robots, Cara must decide whether to accept her place in a pattern of technology, violence and deceit, or take action of her own.