Embrace the Wolf by Benjamin M. Schutz
First in the series that features Leo Haggerty, Private Eye

I have the admit the first chapter sucked me in. 5 years previously twin 5 year old girls were kidnapped by an unknown person. The kidnappers never made a demand but the father, Herb Saunders, never gave up hope they would come home one day. He had been doing his own investigations to find his daughters so when the kidnapper calls and plays a tape of his daughters voices he is off to find the fiend who stole them. His wife returns home to find a note saying he was going to find the devil so she calls in Leo Haggerty to help bring her husband home.

I should have stopped reading it after the first chapter and just skipped to the ending. This is a very tragic book that has a lot of horrible sex and torture that I could have done without. I'm reading his latest book Mongol Reply that is so much more interesting. Perhaps someday I'll try his Leo Haggerty books again.