It’s understandable that Clint Eastwood, at age eighty, should want to muse on the subject of mortality and what follows death. It may even be reasonable that Peter Morgan, who’s shown his writing talent in fact-based dramas like “The Queen” and “Frost/Nixon,” should have chosen to stretch with a script that juggles plot lines in the fashion of Guillermo Arriaga. But “Hereafter” proves a disappointment for both of them.

It’s very well mounted, of course, like all of Eastwood’s pictures; his production team continue to do unostentatiously first-rate work, from Tom Stern’s elegantly straightforward cinematography and James J. Murakami’s design to Patrick Sullivan’s art direction. And in an opening scene involving a destructive tsunami, the visual effects team headed by Michael Owens gets to show off its stuff.

But the picture is basically a lot of hooey about the notion that ordinary people’s fear of dying and a conspiracy of silence have effectively closed off consideration of the ultimate reality. It brings together a trio of stories. The first is of French television journalist Marie LeLay (Cecile de France), who after suffering a near-death experience when engulfed in the tsunami’s waves that includes white lights and willowy figures, loses her interest in ephemeral present-day matters and instead chooses to investigate (and write about) what actually comes after death. The second deals with George Lonergan (Matt Damon), a morose American psychic who can actually converse with the departed but has chosen to cease doing so—seeing the power as a curse rather than a gift despite the urgings of his commercially-minded brother (Jay Mohr) to take advantage of it. And then third centers on Marcus, a reserved English lad pining over the death of his beloved twin brother Jason and longing to make contact with him again. (The boys are played by George and Frankie McLaren, who apparently shared the roles.)

For the most part these three plot threads are followed separately as Morgan and Eastwood jump from one to another and then back again. So we follow LeLay’s problems with her TV bosses and skeptical publisher; and George’s attempt to make a normal connection with Melanie (Bruce Dallas Howard), an ebullient young woman he meets at a cooking class, while dealing with the loss of his job at a sugar factory; and Marcus’ unhappiness when he’s placed with a foster couple after his addict mother is carted off to a treatment facility. It all comes together, however, at a London Book Fair, where George has gone to hear Derek Jacobi reading from his favorite author (Dickens), Marie has traveled to hawk her book on the afterlife, and Marcus has been taken by his foster parents to meet one of their earlier guests who’s now a security guard. The trio meet in various cute-but-teary ways, and there’s an entirely too effortful leap to a comfortingly romantic conclusion that links George and Marie. (Its effectiveness might be measured by the fact that their apparently destined connection occurs not, for example, at the Empire State Building—as in “An Affair to Remember”—but at a London Pizza Express.)

Eastwood treats all this with an alarming lack of humor, failing to bring to this material the sort of understated touch he managed even in a picture like “Gran Torino,” which dealt with a serious subject like racial bigotry but did so without hammering it into the ground. By contrast “Hereafter” is unrelievedly somber and slow, giving a gloomily portentous feel to ideas that aren’t nearly as profound as the makers seem to think. The approach pretty much hamstrings the actors, with Damon and de France, both vibrant people, stuck in their characters’ doldrums until the very last moment. The McLarens cut loose a little earlier than either of them (and have some fun in their initial scenes, too), but are still trapped by the overly fatalistic script. A few moments of lightness are provided by Mohr, Howard and Jacobi, but most of the supporting cast are constrained by the overall air of heaviness as well, and the very deliberate pacing in Joel Cox and Gary D. Roach’s editing merely accentuates the atmosphere of plodding solemnity.

It’s inevitable that a movie dealing with the afterlife will lack unsatisfying answers. What’s disappointing about “Hereafter” isn’t so much that Eastwood and Morgan are unable to provide them, but that their effort to address the questions proves so dramatically inert.