“The Boy Behind the Door” is a lean, reasonably tight B-movie thriller about two kidnapped Little Leaguers and how they respond to their plight.

It’s sentimental yet nervy, kind of predictable and a tad slow-footed. But it gets to you in all the right ways and in all the right places.

Bobby (Lonnie Chavis) and Kevin (Ezra Dewey) are best buds, “friends till the end” they promise, who long to escape their corner of South Dakota.

Instead, they’re clubbed unconscious and kidnapped on their way to Little League. Kevin is yanked out of the car trunk, screaming and crying. Bobby is locked-in and left behind. Which gives him time to weep and scream and then reason and kick his way out.

But making his escape, his conscience and the sound of Kevin’s cries drag him back. He will slip into the house and free his friend, come what may. His first communication with his shackled pal has good news and bad. Their tormenter “is gone.”

“What about the OTHER one?”

Movies like this are filmmaker and film character problem-solving exercises. The kidnapper dialogue may be banal and empty — “You don’t have to hide from me. I just wanna TALK.”

What matters is the possible solutions Bobby and Kevin see to their plight. Can I use this? What if I try that?

The stumbling blocks are stronger, murderous adults, the remoteness of their location, old fashioned locks, the mystery of “land lines” and manual transmission cars, and newfangled gadgets meant to entrap or disable.

The young players do a decent job of suggesting the terror their perilous situation makes them feel. The villains are villainous in some of the usual ways.

Co-writers/directors David Charbonier and Justin Powell may slow-walk some of the between-fights action. Victims are always getting the drop on their tormentors and leaving the job unfinished, leaving a weapon behind, not getting out when the getting’s good.

But that’s part of the fun.

MPA Rating: unrated, graphic violence

Cast: Lonnie Chavis, Ezra Dewey

Credits: Scripted and directed by David Charbonier and Justin Powell. A Shudder release.

Running time: 1:28