As mainstream Hollywood studio movies go, “Night at the Museum: Secret of the Tomb” isn’t bad. I’ve seen my share of bad sequels and this isn’t one of them, although the setting couldn’t be more familiar. Ben Stiller is back at it again and this time he’s on a very serious mission: he has to go to London’s British Museum to solve a mystery that is threatening the existence of all our favorite New York Museum exhibits, from Teddy Roosevelt (the late, great Robin Williams in his last on-screen appearance) to cowboy Jedediah (Owen Wilson) and centurion Octavius (Steve Coogan). All the newcomers score points, including Dan Stevens as Sir Lancelot and Sir Ben Kingsley as a pharaoh. Once again, director Shawn Levy has gathered a fine cast and he makes great use of his locations, including a funny chase scene all around the city of London. It’s such comic moments that lift “Secret of the Tomb” above the herd. Kids will enjoy the sheer novelty of it, while grownups will get a chuckle seeing Hugh Jackman in a very funny cameo appearance. And yet, with all its ups and downs, the movie still rests on the shoulders of Stiller and his ability to make us root for him. In spite of various story contrivances we do, on the most elemental level, and that’s why this sequel clicks. Will I remember plot details in a week or so? Probably not. But the top cast makes the jokes (even the lousy ones) go down easy.