One of the nicer things about “Ant-Man,” the 2015 origin story of the eponymous Marvel superhero, was its modesty and congeniality. The film kept things light, its playfulness made all the more endearing by the boyish, twinkle-eyed persona of its star, Paul Rudd.

Returning in the title role, Rudd brings those same exuberant values to bear on “Ant-Man and the Wasp,” which makes up in brio and adorability what it might lack in narrative complexity.

As the movie opens, Rudd’s “real-life” alter ego, Scott Lang, is wrapping up his house arrest since the mayhem of “Avengers: Civil War.” With only three days to go, he spends his time fooling around on his drum machine, practicing card tricks and amusing his daughter, Cassie (Abby Ryder Fortson), by staging pretend heists.

Ostensibly, Lang’s past life of crime now will be erased by the domestic duties of a single dad and the security firm he runs with his former cellmate, Luis (Michael Peña). But before the LoJack comes off, he’s drawn into another adventure with inventor Hank Pym (Michael Douglas), Pym’s daughter, Hope (Evangeline Lilly), and Hope’s long-lost mother, Janet (Michelle Pfeiffer), who has been miniaturized and trapped for 30 years in the quantum realm, but who now might be capable of returning — with Ant-Man’s help, of course.

The plot isn’t the thing in “Ant-Man and the Wasp,” which distracts viewers with the usual gizmos that light up, whir, shrink-o-late and supersize with metronomic regularity, as well as a complement of credible bad guys, led by a toothy greed-head named Sonny Burch (Walton Goggins).

The joys of the movie lie in its utterly gratuitous but amusing digressions.

Much of “Ant-Man and the Wasp” feels like filler, especially when the fight between the forces of good and evil is triangulated by characters played by Laurence Fishburne and Hannah John-Kamen. Everyone gets their arc in a movie that feels less urgently necessary than shruggingly self-accepting.

Directed by Peyton Reed from a script by Rudd and a raft of co-writers, “Ant-Man and the Wasp” serves its purpose with a characteristically sunny disposition and occasional flair, situating its various heroes, villains and sidekicks for future installments and moving the Marvel behemoth ever forward. It’s merry and fleet, and no less enjoyable for being instantly forgettable.