New York City cab driver Yuri Davydov is a disgruntled Russian émigré poised to lash out at the adoptive nation he believes has denied him the American Dream. A former technician in the Soviet Union's biological weapons system programmes, Yuri possesses the knowledge to wreak havoc in his new home. But before hr executes his planned pièce de résistance of vengeance, he experiments on selected targets. Dr Jack Stapelton and Dr Laurie Montgomery (both last encountered in Chromosome 6) begin to witness some unusual cases in their capacity as forensic pathologists in the City Medical Examiner's office: a Greek immigrant succumbs to what at first seems a sudden overwhelming pneumonia; an obese Afro-American woman collapses with acute respiratory distress. When an unexpected coincidence persuades Jack that these seemingly unrelated deaths are connected murders, his colleagues and superiors remain sceptical. Meanwhile Jack is taking himself deeper into deadly danger - but can reach the heart of the puzzle before Davynov and his associates unleash into the street of New York the ultimate terror: a modern bio-weapon?