A vehicle crammed with dozens of dead Chinese immigrants is found in southern Texas. Pathologist Margaret Campbell must put aside her horror, and find out why. SUMMONED Detective Li Yan - an even more unwelcome memory for Campbell - has arrived stateside to investigate a link in the case to a lucrative trade in illegal labourers. SNAKEHEAD Li and Campbell will soon find that the crime scene hides another secret: a biological time bomb linking traffickers, politicians and migrants in Beijing, Washington and Texas - posing multiple countries one, very singular, threat.