tavis: up next, actor mark harmon, stay with us. please welcome mark harmon back to this program. he stars on "ncis," which has become one of the most watched series on television. the shower airs tuesday nights at 8:00. here now a scene from "ncis." >> i need a lead. >> oh, really? because i found our killer's blood. how is that for a case cracker. guess where. no, really, like i want you to guess. >> on the knife. >> no. guess again. >> abby -- >> i found trace amounts inside the stab wounds of our latest victims. >> d.n.a. >> i read the d.n.a. through the database. there is nothing in the system. but guess what mcgee thought? >> abby, no more guessing. credit cards, he purchased a hunting knife. >> the murder weapon. >> the point and spine of this matches the wound patterns of all five victims. tavis: you must know something that other folk on tv do not. you're in season seven. tavis: up against "american idol" no less. >> always have been. tavis: you're my man, first of all. >> you're my man. tavis: how do the heck to you survive seven seasons up against that? >> tavis, we con