First-year detective Kathleen Doyle is a plucky Irish redhead. Chief Inspector Michael Acton is a British lord turned cop. He's tall, handsome and enigmatic - to a fault. Acton selects Doyle to partner with him on a series of investigations because she always knows when someone is lying. Sent to investigate a murder, the pair are dragged into ever more perilous situations - but the real danger is the unlikely attachment that develops between them, raising hackles among their colleagues at the Yard.