LL Cool J Paves Way for Possible 'NCIS' Spin-off

ET is with LL Cool J as he joins Mark Harmon on the set of "NCIS dvd." This exclusive takes you inside theepisodes that could lead to a possible spin-off show.Cool J and Chris O'Donnell will appear on two episodes of "NCIS" to set up a series that is beingconsidered to debut this fall.Special Agent Sam Hanna (Cool J) and G. Callen (O'Donnell) are from the NCIS dvd Office of SpecialProjects and team up with Special Agent Timothy McGee (Sean Murray) and Jethro Gibbs (Harmon) tosolve the murder of a U.S. Marine.Watch this ET exclusive to hear LL talk about his gun training and the pressure to "not mess up"when acting on one of the highest rated shows on television. The "NCIS dvd" special two-part story begins Tuesday, April 28 on CBS.