There’s a lot to unravel in Mindhunter.

The new Netflix series (streaming Friday, ** ½ out of four) comes from Gone Girl director David Fincher and follows two FBI agents (Jonathan Groff and Holt McCallany) in the 1970s whose work helps develop the practice of criminal profiling.

Based in part on former FBI agent John Douglas and writer Mark Olshaker's 1996 non-fiction book, Mindhunter likely will please fans of Fincher and true crime. It’s slow-burning, dark, dense, graphic and character-driven. Its shots are moody and well-composed. And its heroes — Groff’s earnest Holden Ford and McCallany’s gruff Bill Tench — are appealing, and flawed mostly by their over-eagerness to do good.

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But Mindhunter, at least in the first two episodes made available for review, is also meandering. It’s not as tight and gripping as Fincher’s earlier Netflix series, House of Cards (at least in the early episodes that Fincher directed), and feels less like a cohesive TV series and more like an extended film. For some, that may be a bonus, but on Mindhunter the overall effect is a sense of listlessness, which is odd considering the urgency of its subject matter.

The series opens with Ford, a young and promising FBI agent who specializes in hostage negotiation, being re-assigned to headquarters in Quantico as an instructor. He’s struck by a fellow teacher’s lecture on crimes without motive, strangers who kill strangers. He digs further into this topic and eventually is partnered with Tench, who heads up the behavioral science department, and the pair hit the road, attempting to educate police departments across the country.

While in California, Ford visits Edmund Kemper in an effort to find out how his mind works. (Cameron Britton plays the real-life killer.) Their investigations into criminal minds take off from there.

The series spends most of its first two hours sending Ford and Tench on the road, and in agreement about their mission.

Once they get going, however, there are some compelling storylines within the series. In particular, the scenes in which Ford interviews Kemper are sharply written and engrossing, if a little discomfiting.

Despite Netflix’s affinity for “binge-able” series, Mindhunter is unlikely to be enjoyed all at once. It is a narrative consumed by violence and sometimes shows intensely graphic imagery of the murders perpetrated by its killers.

Although scenes are strung together a bit casually, they are lavishly filmed, meticulously directed and scored. Groff and McCallany are well-cast, and Groff has an air of innocence and naiveté that makes his goody-goody character work.

But overall, the series lacks sharpness. The first two episodes feel almost deliberately incomplete, begging for something bigger to arrive, the same way that Ford calling Kemper a “sequence killer” begs to be rephrased as “serial.”

Later episodes could tighten Mindhunter, but so far it seems more like a series close to the mark than one that hits it.