Marketplace joins forces for the fourth time with contractor Mike Holmes, this time to investigate the shady world of shoddy roofers. Co-host Erica Johnson discovers that some roofers are experts at taking your money, eluding the authorities, and re-inventing their companies -- but not so great when it comes to protecting your house. We set up a "bait house" -- badly in need of a new roof, and equipped with hidden cameras -- and watch as a surprising number of roofers fail to meet Mike Holmes' checklist of "good roofing 101." Then we chase the stories of two roofers with a trail of unhappy customers -- and tracks down the roofers themselves.