keith morrison: --whose long silence was about to end. coming up, and end it would, with a bang, with stories of who she said was the real mark stover. and he had a pistol in his hand and laid it on the pillow next to my head. i see mark on a hillside behind my house. he's looking through the scope, pointing the rifle at me. keith morrison: when "dateline" continues. 3 days is really fast. sensitivity, the dentist is going to be able to provide that to their patients. sensodyne rapid relief in my opinion is a game changer. it's going to let the dentist offer their patient sensitivity relief in 3 days. it has a formulation that lays down a barrier of protection against sensitivity. within 3 days, say over the course of a weekend you're going to start feeling significant results. to say that it works in 3 days really is a big deal.