Night at the Museum: The Secret of the Tomb begins within the Egyptian tomb of its title, but since this is the third Museum flick, there are precious few secrets left. The big reveal this time around is that the magic is wearing off — which seems a good metaphor for this joyless sequel, itself. Spoilers ahead...
In the third Night movie, Larry Daley (Ben Stiller) — back in his element as night security guard at the Museum of Natural History after part two's Smithsonian sabbatical — is now not only completely comfortable with the fact that the exhibits come alive at night, he's totes fine with pressing his stuffed, wax, miniature, etc. friends into service.
And after a brief interlude among the pyramids in which we learn "the end will come" via a certain cursed tablet, we're dropped into a museum fundraiser populated by rich folks and long-dead historic figures. (Among their ranks are familiar faces from the previous films, including Robin Williams as Teddy Roosevelt in one of his last roles; Shawn Levy, who helmed the first two films, also returns to direct.)
Since there must be conflict, or at least some suggestion of conflict, when the normally jolly museum dwellers begin to act out of character, it's discovered that the Golden Tablet of Akhmenrah, which gives the exhibits their nighttime juju, is starting to deteriorate. Oh, you thought "the end will come" meant the end of the world? Nope. This movie's biggest worry is that the ancient relic's powers will diminish so much that the likes of Steve Coogan, as a teeny Roman, and Crystal the Capuchin Monkey, as Dexter the Capuchin Monkey, will no longer get to goof off in the halls after sundown.
With stakes that high, there's nothing for Larry to do but head to London's British Museum and ask the parents of Akhmenrah (Rami Malek) for advice, since they made the damn tablet in the first place. Naturally, the entire gang, including Larry's teenage son Nicky (whose career ambition is to be a DJ in "Ibi-tha"), makes the trip to London (of course "London Calling" underscores their arrival) for some shenanigans, which include waking up the London museum's exhibits for the first time.
New faces in this installment include Rebel Wilson as a British Museum night guard who has an endearingly bizarre flirtation with one of the Neanderthal exhibit-dwellers (also portrayed by Stiller), and her saucy energy is a welcome addition. Another bright spot comes courtesy of a bit that has the characters racing up and down the stairs within an M.C. Escher drawing. Then, there's Dan Stevens rocking a pageboy as Sir Lancelot with such enthusiasm that it only highlights how much everyone else is just kind of going through the motions clad in ridiculous costumes; his insistence on calling Jerry "dangly bells" (because Larry reminds him of a court jester he once knew) is a dumb joke that actually works. Less successful is Lancelot's encounter with a Famous Actor Playing Himself who Lancelot insists on referring to as "Huge Ackman." (Get it? Get it? GET IT?)
Tomb's themes don't go much deeper than "fathers and sons need to understand each other" and "friendship is important;" its main draw is the physical comedy enabled by the film's judicious use of CG to enhance everything from a cranky dinosaur skeleton to stuffed animal heads mounted on the walls. Unfortunately, and despite obviously strenuous efforts on the film's technical side (noses melt! Faces begin to crumble!), the laughs don't really come freely, or at all. Tomb offers literal enchantment galore, but it's surprisingly lacking much imagination.