Héctor, who is “Seventeen,” is the troubled loner everybody in his Spanish reform school picks on. The kids — all reprobates, like him — ridicule the way he took the judge’s edict that he use his two years confined there studying the Spanish criminal code, “to learn the difference between right and wrong,” she says (in Spanish, with English subtitles).

The kids call him “Abogado” (lawyer) and steal his criminal code book from him.

But the fuming, on-the-spectrum Héctor will fix them, we assume. We see him scheming and working in wood shop. He’s machined and carved a stake! When he finishes it, he scrawls a number on it.

He cadges some masking tape and lashes the reformatory-issued slippers he wears to his feet.

First chance he gets, he bolts across the soccer field, scrambles up over the high fencing, just outrunning the guards, and sprints down a path…past other stakes.

When he’s caught, even though he’s very, very fast, he sticks that stake in the ground to mark how far he got on attempt number 20.

“Seventeen” lives on such moments, a little “Cool Hand Luke” there, a hint of every feuding siblings on a quest comedy here, with just enough of Héctor’s (Biel Montoro) ingenuity in all things petty criminal (we’ve seen him steal a motorcycle and break into a mall as it closes in the opening) for his brother Ismael (Nacho Sánchez of Netflix’s “The Ministry of Time” series) to ask him the question we all are by the film’s midway mark.

“Now what, MacGuyver?”

Daniel Sánchez Arévalo — he did “Gordos, (Fat People)” — tells us a story of brothers, a dying grandmother, a missing dog and a cownapped cow in this smart and amusing, if slow-moving, dramedy.

The dog in question is the first sign the audience, and Héctor’s in-school counselor (Itsaso Arana) have that there’s humanity in him. He seems to take no pleasure in his shoplifting, mall-crashing and motor-scooter theft. He wears one expression all the time –sullen. He blames brother Ismael for his incarceration.

An abused therapy-mutt he is assigned lets us see him care about someone or something else. He names the fuzzball “Sheep,” trains him and gives him love, which we were beginning to wonder if he was even capable of.

Then the dog is adopted out. And this time, Héctor’s stake stays in his pocket. He makes his get-away.

He finds his brother living in an RV. “Marta” kicked him out. Ismael knows the kid only has two months left in his sentence. Héctor’s two days shy of his 18th birthday. Any crimes he commits while they look for the people who adopted this dog will get him put in prison, after two days.

Oh, and there’s their abuela (grandma). She (Lola Cordón) is dying, and before they can find the mutt, they must check granny out of the home so they can grant her dying wish — to be buried next to her late husband in the village of their youth.

So we’ve got a kid on the lam, a heart-broken older brother who raised him and wants to give up on him the way Marta gave up on him and a very old woman whose oxygen intake is falling by the hour.

“Dark comedy” is “comedia oscura” in Spanish, fyi.

But “Seventeen” reaches for more than that. It lets us see how this dog is just outside proof of the feelings he’s capable of, an extension of how he’s doted on his grandmother. The hunt of the adopted dog underlines that. He won’t leave a dog they find in a junkyard, refusing to leave the loyal but now sickly animal in the minivan he was in when his master died in a car crash.

I can’t say “Seventeen” sprints by, but its many grace notes make up for the slack pace.

MPAA Rating: TV-MA (criminal behavior, alcohol)

Cast: Biel Montoro, Nacho Sánchez, Itsaso Arana, Chani Martín and Lola Cordón.

Credits: Directed by Daniel Sánchez Arévalo, script by Araceli Sánchez and Daniel Sánchez Arévalo. A Netflix release.

Running time: 1:39