“God’s Crooked Lines” is a modestly complex hybrid thriller, a blend of “Who is telling the truth, who is gaslighting whom?” and “Is this real or is this in my head?” stories, naturally set in a mental institution.

A good measure of such a movie is how often it makes us guess wrong and how invested we remain in it to the very end. Clocking in at a mini-series length two and a half hours, this Spanish production falls short of the mark in both regards.

But Spanish director and co-writer Oriol Paulo, who gave us “Mirage” and the Netflix series “Inocente,” stages some fine set-pieces and creates a properly gloomy tone for this Around the World with Netflix mystery about a woman who claims she’s gone undercover to investigate a crime at a mental hospital, an asylum whose doctors dismiss that as the ravings of a rich woman who poisoned her husband.

As we meet Alice Gould (Bárbara Lennie of “Petra”), she’s riding to the Our Lady of the Fountains Hospital at the behest of the man driving her. He lost a son there, she later says. And she’s an experienced investigator who has agreed to go inside, find out what the saner inmates are saying, and poke around in the archives to see if the staff is covering something up.

That’s her story, that she’s “voluntarily” committed herself here to that end. But the hospital doctors maintain that she tried to poison her husband, that she’s “very dangerous” and “unstable” and a “masterful liar” (in Spanish with subtitles, or dubbed into English).

There’s no argument over whether she’s beautiful, which she is, or that she’s a natural redhead, which she isn’t. We see her roots growing out within days of her arrival.

Another fact left dangling as “Alicia,” as the informal staff insists she go by, is rich. So, she’s a…gentleWOMAN detective, like Benoit Blanc of the “Knives Out” mysteries?

That’s Netflix, beating a clever idea to death.

It’s about 1980, and we see Alice investigate, ask questions and try to befriend the more sentient inmates like the special privileges oddball Ignacio (Pablo Derqui) and keep at least some of the staff in the loop, or out of it until she can meet with the director of the place, Dr. Alvar, who is privy to her investigation.

But when he (Eduard Fernández) finally shows up, he contradicts her, punches holes in her story and makes us question if she’s a reliable narrator of her own life. Has she been “legally kidnapped,” sent here by a greedy husband out to steal all her assets, with perhaps inside help from the hospital? Or is she the “masterful liar” Dr. Alvar bluntly claims she is.

There are deaths inside the hospital in this story, a tale told out of order in some places to throw us off the scent. An escape attempt leans on that almost fool-proof “How to get yourself out of a hostage situation” trick — fire.

The cops are involved, and skeptical. The staff seems divided. And the inmates are either helpful or chillingly out to molest or murder her. So she says. So she might think.

A few scenes pop, but the entire enterprise played as low-heat to me, with little suggestion this woman is crazy, or alarmed that she might wind up trapped inside an insane asylum by a plot that’s tripped her up.

The stakes are neither high nor low, as we don’t know what is real and what isn’t and Alicia’s part in that.

The shuffled order of the storytelling robs the picture of pacing and urgency. The only reason to make this a period piece, aside from a few jabs at Freud and sexist Spain circa 1980, are to deny our heroine cell phone access, I guess.

The plot may meander a bit, following “God’s Crooked Lines” as it does. But in this hemisphere, at least, we see this handsomely mounted but tepid tale’s finish line an hour or more before everyone in the cast.

Rating: TV-MA, violence, profanity

Cast: Bárbara Lennie, Eduard Fernández, Loreto Mauleón, Pablo Derqui and Antonio Buíl

Credits: Directed by Oriol Paulo, scripted by Oriol Paulo and Guillem Clua. A Netflix release.

Running time: 2:34