SERIES PREMIERE: The popularity and durability of this CBS series, itself a spinoff of another series (JAG, which began on NBC and was rescued from oblivion a season later by CBS), is by now a modern marvel. Tonight, for NCIS, is the Season 15 premiere, more than twice the length of the usual run of a successful broadcast drama series. And Season 15 begins by continuing with last season’s cliffhanger drama, months after Gibbs (Mark Harmon) and McGee (Sean Murray), in mid-mission to locate a missing Navy SEAL, were captured by rebels in Paraguay.