The lambdas, who appear to be aliens from a distant sea, are genetically human. They slide into low- to middle-income occupations silently and pretend to want nothing more than to be alone. They are first a frightening presence in Cara Gray's otherwise ordinary childhood, then the enigmatic target of her police surveillance work. A shadowy gang of lambda extremists claimed responsibility for a school bombing, but how could a defenceless community of small aquatic humans, scarcely visible in society and seemingly oblivious to their own exploitation, be capable of something so horrific? In Cara?s world a toothbrush can be legally alive, a quantum computer has the power to decide who dies, and a government employee made of slime mould protein needs help to relieve his neuroses. As Cara?s relationship with the lambdas deepens, she must decide whether to accept her place in a pattern of technology, violence and deceit, or to take action of her own.