Night at the Museum: Secret of the Tomb Ben Stiller, Robin Williams, Dan Stevens. Directed by Shawn Levy. Rated PG. Opens Friday.

Made from the “kids-won’t-care-how-badly-we-slapped-this-thing-together” school of filmmaking, Night at the Museum: Secret of the Tomb is the third in a series of money-makers based on funny actors and lots of visual effects.

The plots are secondary, like this one: The magic tablet that brings exhibits to life in New York’s Museum of Natural History begins to lose its power, so security guard Larry (Ben Stiller), his son (Skyler Gisondo) and a bunch of the exhibits go to London to consult Merenkahre (Ben Kingsley). There, Sir Lancelot (Dan Stevens) gives them plenty of trouble. Director Shawn Levy and his army of writers bring up ideas, and let them drop.

Clumsy cutting ruins many of the jokes, and the action sequences are lifeless. Owen Wilson’s lackadaisical line readings are worth a giggle or two, though. And the final goodbye as Teddy Roosevelt (the late Robin Williams) returns to wax is bittersweet, but not because of anything the movie has done.