The edge-of-your-seat climax to “Strange But True” may trick you, for a moment or two, into forgetting how so much of what came before it seems as if it was from another movie.

One doesn’t have to see “based on the novel by John Searles” in the opening credits to figure out that this is an adaptation, and a pretty clumsy one at that. “Adaptation” give-aways include a large muster of characters, ungainly synthesizing of themes and ideas and abrupt shifts in tone and focus.

This damned thing is all over the place — warm fuzzies to edge-of-your-seat violence.

For much of “Strange But True,” we’re in mourning with characters who have let that emotion take over their lives.

Former librarian Charlene (Amy Ryan) is wearing this most openly. Brittle, bitter and snappish, we come to see how she lost her career and her marriage, and the last two spun out of losing her oldest son.

Younger son Philip (Nick Robinson of “Jurassic World” and “Everything, Everything”) is on crutches, home from college and still struggling to cope with the death of brother Ronnie.

Husband/dad Richard (Greg Kinnear) has started over, moved to Florida with “his trophy wife,” Charlene fumes.

But the person taking this the hardest might be the very pregnant young woman, Melissa (Margaret Qualley of “Seberg” and “Once Upon a Time…in Hollywood”). She shows up at their door with a story about “some strange miracle” that’s happened.

Ronnie’s onetime girlfriend is carrying his baby. Wow. He died, what, five years ago?

“I’m not crazy,” she insists, playing by a psychic reading she recorded on cassette. “I’m not stupid.”

We’re not convinced any more than Charlene.

“Are you looking for money?”

The story that we think we’re watching unfold tells us what happened to the kid and everyone around him via flashbacks, Charlene’s investigation (at the library) of “how this (pregnancy) could be possible” and Philip’s efforts to figure out what’s really going on with Melissa.

There are friendly neighbors (Blythe Danner and Brian Cox) looking out for her, and pieces to a mystery that Charlene and Philip, working independently and seemingly at odds, will pull together.

And that sad, grieving vibe that director Rowan Athale (“Wasteland”) is reaching for? We can’t forget that the first scene of the movie is Philip, hobbling on crutches as he’s chased into the woods. The “mourning” story is a flashback getting us back to that point.

There are some good red herrings here, false leads to pursue fed by casting, the way new information is allowed in, drip by drip.

Ryan is at her most ferocious, stepping into a workplace she was “fired” from years before, sweetly greeted by old colleagues she resents and ready with the perfectly acidic comeback.

“Every day’s a blessing.”

Robinson is more the focus here, but the character and the performance aren’t interesting enough to hang the movie on.

Qualley has a sad sparkle about her that makes us wonder why the entire film isn’t her “journey.” Losing track of her is its fatal flaw.

There’s something to be said for a story that knocks you backwards a few times and keeps you wrong-footed. But the whiplash this somber, intimate tale gives you in its “Wait, WHAT?” third act is another matter altogether.

The logic is strained and the twists so over-the-top that it would pretty much have to be “Strange But True” for us to ever believe a bit of it.

But it’s not. It’s fiction, far-fetched, everything-but-the-kitchen-sink, beach-book thriller fiction. It provokes many reactions, but the one that stands out is “cheated.”

MPAA Rating: PG-13 for mature thematic elements, some violence, suggestive material and brief strong language

Cast: Amy Ryan, Nick Robinson, Margaret Qualley, Blythe Danner, Greg Kinnear and Brian Cox.

Credits: Directed by Rowan Athale, script by Eric Garcia, based on the John Searles. A CBS Films release, on Netflix.

Running time: 1:36