Sean Duffy knows there's no such thing as a perfect crime. But a torso in a suitcase is pretty close.

Still, one tiny clue is all it takes, and there it is. A tattoo. So Duffy, fully fit and back at work after the severe trauma of his last case, is ready to follow the trail of blood -- however faint -- that always, always connects a body to its killer.

A legendarily stubborn man, Duffy becomes obsessed with this mystery as a distraction from the ruins of his love life, and to push down the seed of self-doubt that he seems to have traded for his youthful arrogance.

So from country lanes to city streets, Duffy works every angle. And wherever he goes, he smells a rat...