As funny and charming as they come, Paul Rudd (Anchorman 2: The Legend Continues) is, as expected, the best thing about Ant-Man. Give Marvel Studios that much: From Robert Downey Jr. to Chris Pratt, their casting instincts are so reliably solid, they’re uncanny. Their storytelling prowess? We’ll get to that.

Rudd’s Scott Lang is the “good” kind of criminal: a well-intentioned, modern-day Robin Hood who redistributes wealth from a bullying corporation and earns a prison sentence for it. Once out, his felonious exploits also earn him a freelance gig of sorts, carrying the torch of scientist Dr. Hank Pym (Michael Douglas, Haywire) by succeeding the disgraced genius as the superhero Ant-Man. Decades before, Pym developed the technology — and accompanying helmet and suit — that allowed him to shrink to the size of … wait for it … an insect, and gain in muscle what he loses in mass.

Pym long ago abandoned his avenging ways because he was afraid of his invention falling into the wrong hands. One such pair of greedy mitts belongs to his former protégé, portrayed by Corey Stoll (Non-Stop). So ineffectual and thinly drawn is Stoll’s villain that if the chrome-domed actor were capable of growing hair on his head, a mustache for him to twirl would not be out of place. It is not the fault of Stoll that until the more inventive second half, Ant-Man tends to slow and sputter when director Peyton Reed (The Break-Up) pays attention to this master-vs.-pupil portion of the narrative; from the sidelines, Rudd can do only so much to keep the film loose and lively.

Call it the curse of the origin story: So much of the movie is spent setting itself up that once it really gets going, half of it has passed. Scenes like Ant-Man’s sparring with The Falcon (Anthony Mackie, last glimpsed in Avengers: Age of Ultron) and the final one involving Pym and his daughter (Evangeline Lilly, Real Steel) are what make one excited by the closing credits’ promise that “ANT-MAN WILL RETURN.” —Rod Lott