Night at the Museum heads to London because this is a logical journey for museum manikins to make. But more importantly it looks like the magical stones are broken, which could mean the death of fake Teddy Roosevelt, and that is not acceptable.
Also it looks like the cat is officially out of the bag on the whole "we come alive at night," thing. Which is weird, but it doesn't matter because this movie is cute.
I have nothing bad to say about the third Night at the Museum movie. These are nice movies for kids that do no harm to our younger generation. Go in peace, Night At the Museum.