(NBC) — NBC’s “Law & Order” and “Law & Order: SUV” return for new seasons on Thursday. The original “Law & Order,” often called the “mothership,” returns with a new boss. Two of the show's stars talked about the newcomer. Last spring, Detectives Shaw and Riley were caught off guard on “Law & Order” when new D.A. Nicolas Baxter showed up at their crime scene. The duo gets another surprise Thursday when their new boss also shows up unannounced. Dermot Mulroney shakes things up on NBC’s ‘Chicago Fire’ as new chief “’Law & Order’ is, is zero to 100, and it just, it drops the case on you like that, it drops the murder on you like that, it drops the characters on you like that,” said Mehcad Brooks, who plays Detective Jalen Shaw. The character dropping on Thursday is Lieutenant Jessica Brady played by Maura Tierney. “It's like watching a master class every time she's on set,” said Brooks. Tierney's character takes over for Kate Dixon, played by Camryn Manheim, who had a tight working relationship with Detective Vincent Riley, played by Reid Scott. “Even small obstacles, like getting a new lieutenant out of nowhere, it makes the job more challenging,” said Scott. And almost instantly, there's tension between Riley and the lieutenant. “Riley's the kind of guy he doesn't like to be told what to do,” said Scott. “He doesn't like to be pushed around. He doesn't like surprises.” But surprise is part of the intrigue for “Law & Order.” “Law & Order” airs Thursday at 8 p.m. on NBC4, followed by “SVU” and then, at 10 it is the missing persons drama, “Found,” in a new time slot as it begins its second season.