Chinese artist Ai Weiwei spent 81 days in detention for “subversion of state power,” then spent a year under house arrest, as documented in Andreas Johnsen’s film. (Andreas Johnsen)

Alison Klayman’s 2012 documentary portrait “Ai Weiwei: Never Sorry” introduced us to the Chinese artist Ai Weiwei, in the months leading up to his 2011 arrest and imprisonment for “subversion of state power.” It offered an engrossing look at both the artist’s protean creative practice — a brand of conceptualism spanning photography, performance, sculpture and the prodigious use of social media — and his habit of political provocation.

Andreas Johnsen’s follow-up, “Ai Weiwei: The Fake Case,” picks up the story upon Ai’s release from his 81-day detention. But the film is hampered by the fact that Ai, on the occasion of his parole, seems a chastened, well-behaved shadow of his former, unrepentant self. One of the first scenes in Johnsen’s film shows the seemingly traumatized subject apologizing to a journalist for not being able to talk.

Good lord, who wants to see a movie about that?

Fortunately, Ai eventually comes out of his shell, albeit slowly and painfully. Until he does, the movie is a mite on the dull side, showing us a taciturn, creatively blocked man, prone to taking unplanned naps between play dates with his young son.

The turning point comes when one of the artist’s assistants is roughed up by the police permanently stationed outside Ai’s studio during his yearlong house arrest. Ai explodes in anger, striding outside to yell and curse at the cops. Though the timing of this outburst is unclear, from this point on Ai seems more himself. He’s more emboldened in stating his opinions on camera, and we start to see him working on a powerful six-piece sculpture called “S.A.C.R.E.D.” (which featured lifelike renderings of his imprisonment, and which had to be smuggled out of China to be shown in the 2013 Venice Bienniale, to much acclaim).

Though subtitled “The Fake Case” — a reference both to the cheeky name of Ai’s design firm, Fake, and to the trumped-up nature of the Chinese government’s charges — there’s little in the film about the actual case. That’s due, of course, to the opacity of the Chinese security apparatus, which later added charges of tax evasion to its accusation of subversion. Still, the absence of legal details makes the movie something of a cheat. It offers few insights about the case from the official side, let alone about the machinations of Ai’s legal team.

It’s far more interesting anyway to watch Ai push the limits of his probation, becoming ever more outspoken. At one point, he says, apropos of Chinese government corruption, “If you let me have the radio or free press for one month, I will make the whole thing change.”

It’s a crazily idealistic threat. The man at the beginning of this movie would never have dared to make it. By the end of “Ai Weiwei: The Fake Case,” the man who utters it — a bearlike figure roused from slumber — seems just dangerous enough to mean it.

★ ★ ½

Unrated. At Landmark’s E Street Cinema. Contains nudity and crude language. In English and Mandarin with subtitles. 89 minutes.