a hotel room in winnipeg. lead investigator rob burret monitoring the video in a nearby room. got this elaborate setup. what are you trying to get? >> i've been involved in investigations where we've been able to clear a person of any wrongdoing. so it's not just there to try to find a person guilty. it's there to seek the truth. >> the moment had come. time for denis to come clean. >>> coming up -- his back against the wall, what would denis say to mr. big? >> i'm going to tell you honestly what happened. >> when "dateline" continues. >> when "dateline" continues these are real people, not actors, who've got their eczema under control. with less eczema, you can show more skin. so roll up those sleeves. and help heal your skin from within with dupixent. dupixent is the first treatment of its kind that continuously treats moderate-to-severe eczema, or atopic dermatitis, even between flare ups. dupixent is a biologic, and not a cream or steroid. many people taking dupixent saw clear or almost clear skin, and, had significantly less itch. don't use if you're allergic to dupixent.