Six graves to Munich - Mario Cleri

In the final days of the Second World War, Michael Rogan, an American intelligence officer, is tortured by a group of seven senior Gestapo officers who need to discover the secrets he alone can give them. Ten years later, when he has recovered from the appalling injuries he suffered, and determined to revenge the death of his wife at the hands of the same men, he begins a quest to track down and kill each one of his tormentors. Dark, violent, and graphic, this is an addictive thriller about how far one man will go to exact his own justice.
Written a year before Puzo completed The Godfather, published under a pseudonym and only very recently brought to light, Six Graves to Munich bears all the hallmarks of a master storyteller.