Now is the summer of our discontinued retirement. Harrison Ford’s Indiana Jones returns later in June for “Indiana Jones and the Dial of Destiny.” Meantime, Michael Keaton’s back as Batman in “The Flash,” a standalone DC Comics movie devoted to Barry Allen/the Flash, but periodically elevated by Keaton’s low-keyed, high-impact charisma as Bruce Wayne/Batman. Also the new Supergirl, played by Sasha Calle — she’s good — and feral. The movie is OK and less feral.

Keaton’s introduced as the scraggly, insanely rich hermit landlord and resident of Wayne Manor, pressed into Earth-saving service by two versions of Barry. Ezra Miller, whose Flash zipped around the edges of three previous DC movies, portrays both Barrys, from different timelines. “The Flash,” whose hopped-up title character describes himself as “the janitor of the Justice League,” runs so fast he can revisit the past. This discovery leads to his big idea: saving his mother from a long-ago murder. His father, now in prison, took the rap. Can Barry get around the butterfly effect of his meddling long enough to make his family whole?

This is the storyline, laid out by screenwriter Christina Hodson as a series of entwined spaghetti strands. Director Andy Muschietti, of the demon-clown “It” films, wrangles this project’s frenzied yet unwieldy story requirements, lurching from snark to heartbreak to back-break and back again.

The opening sequence features the Flash plucking dozens of newborn babies, imminent casualties of a collapsing hospital building, out of the sky. That scene carries an intriguing whiff of perversity. It’s more of a grabber, certainly, than the climax, which is the usual DC apocalyptic garbage that sits long enough to create its own alternate timeline.

The movie works like a series of digital Post-it Notes, reminding you relentlessly of related material. Images of Henry Cavill’s Superman, Helen Slater’s Supergirl and other fragments of the DC IP warehouse flit by as Barry navigates the timelines. In these scenes, the digital manipulation of the imagery takes on a deliberately eerie “Polar Express” vibe. Elsewhere, the more conventional digital components are the smallest and simplest: When Barry One teaches Barry Two the art of “phasing,” otherwise known as walking through walls or doors, it’s a matter of the right wheerrrrrooomm sound design combined with an artful visual corollary and presto: It works. It’s funny, and it’s effective.

So much of “The Flash” is neither, despite the budget and the effort. In their earlier, supporting- rank Flash appearances, Miller (who uses they/them pronouns) didn’t have the burden of carrying a project. Here, they do, and Miller’s performances feel strained, pushy, needy, in ways that go beyond the dictates of the storyline. Inevitably this will be interpreted as a direct result of the multiple assault and harassment allegations dogging Miller for years now. Apart from that, Miller’s performances here work too hard. The two Barrys do feel like different characters, and their needling byplay between “slacker” Barry and straight-arrow Barry has its moments. But we never get a moment’s rest, from a character who knows no peace.

Keaton isn’t the only Batman here; Ben Affleck shows up, and there’s a guest star for the epilogue. But Keaton brings both effortless gravity and subtle levity to a film that, without him, wouldn’t have much of either.

MPA rating: PG-13 (for sequences of violence, partial nudity, action and some strong language)

Running time: 2:24

How to watch: In theaters