Hugo” is Martin Scorsese’s engaging adaptation of the children’s book by the same name. What’s it about? It’s an elaborate introduction to a slice of film history. The all-British cast plays out the story set in a 1930s train station in Paris. At first, the story seems to be a misfortunate orphan-urchin tale in the line of “Oliver,” but we can’t help noting that this is no ordinary orphan. Hugo is very good at fixing things because his deceased father was a watch and clock maker (horologist) and taught his son the tricks of the trade. Hugo lives in the train station unbeknownst to anyone and keeps all its clocks running like, well, clockwork. “Hugo” is a total nod to steampunk. There are puffing trains, vents, pipes, chimneys, sewers, as well as plenty of ticking and undulating gears in almost every shot. Steampunk (see also the newest “Sherlock Holmes” movies) is literary movement that celebrates the mechanical age of actual physical, clanking, whirring parts — hardware — that kept everything going, as opposed to our digital world of software and intangible “cloud computing.” Hugo (Asa Butterfield) has an unpleasant run-in with a bitter old toy shopkeeper (Ben Kingsley) in the train station, who recognizes the boy’s genius and eventually takes him under his wing, but Hugo doesn’t seem to be able to keep himself from unintentionally betraying and hurting the already-wounded man. The editing (Scorsese’s longtime editor, Thelma Schoonmaker) really needed to be tighter and faster-paced (with a few disjointed scene-cuts sticking out like sore thumbs). There could have been more camera angles and cuts in general, but on the whole, it’s an eminently watchable film, especially when the film history is delved into and recreated. The threads in “Hugo” are: tinkering with machines, fixing things, everything having a purpose, magician’s tricks, dreams, imagination, film. A theme of the movie is that of children coming too soon and unbeckoned into our lives to mess up our tidy little frameworks, our neat little plans, to pry into our secrets and closed boxes and expose us. And in doing so, they save us.