“Windfall” is a talky, dramatically-flat hostage thriller that’s probably best-appreciated as the most reliable sort of genre piece you can film under a pandemic lockdown.

It’s not particularly suspenseful and not remotely original. But three pretty good actors gather together for a few rich vs. poor, winner-take-all economy and personal responsibility debates, which is just the sort of stuff you haggle over with your kidnapper — in B-movies, anyway.

It begins with some promise. Jason Segel sips orange juice and surveys all that’s at his feet — a luxury hacienda in a remote orange grove right on the edge of the California desert. He gives little away in his expression, and truth be told, we don’t notice his attire until he steps in the posh walk-in shower, unzips his fly, and urinates. That juice glass he throws against a wall? That seals it.

This nameless character is here to loot and rob. And somehow, this expensive, beautifully-stocked getaway has no security system that could foil him.

He’s barely stuffed enough into his pockets to make it worth his trouble when the owners arrive. They’re here for a romantic weekend, and we gather that he (Jesse Plemons) is rich and kind of famous for it, and she (Lily Collins) is his apparently adoring trophy wife.

The husband is calm, barely containing his arrogance and attempt to control the situation.

“You’re not the kind of guy who’d hurt anyone…” “Oh? You already know what kind of guy I am?”

The robber is more the sort who gets right down to business, gets his hands on all the ready cash on hand, the Rolex watch, trashes their phones and “barricades” them in their sauna so that he’ll “have a head start” when he makes his getaway.

But he and we have heard some lies. Making his exit, he spies one more. No, he won’t be leaving. No, they’re not getting off that easily. And that means this is going to take a while.

Segel was one of those with a story credit here, so this thriller without many thrills is sort of his idea. He’s always a convincing Everyman, but we kind of want and expect this fellow to have more overt signs of disturbance or grievance. God knows the husband does.

Plemons is quite convincing as a comfy, soft “fat cat” who has the money to live the higher-than-high life of the one percent, with all the perks and privileges he figures he’s earned. Yeah, he’s going to unload on “lazy freeloaders” who don’t have it as well as he does, and he sells that ethos with ease.

The wife? She’s hearing “get CLOSE to him” suggestions from her husband, something that will make the intruder less likely to harm them. Collins has the least to work with and thus becomes the dullest among the three “types” that this cast is assigned to play.

Everybody here has “secrets,” and as they haggle, bicker, debate and watch “The Three Amigos” on the state-of-the-art outdoor cinema on the back patio, we start to learn them.

No, they’re not as interesting as all that, and no, not every question we have is answered. The former is a problem and the latter isn’t the “air of mystery” asset that this movie needs to come off.

“Windfall” isn’t bad. It’s just predictable and dully inconsequential.

Rating: R for language throughout and some violence.

Cast: Jason Segel, Lily Collins, Jesse Plemons

Credits: Directed by Charlie McDowell, scripted by Justin Lader and Andrew Kevin Walker. A Netflix release.

Running time: 1:32