Grade: C-

Like his previous film “The Lincoln Lawyer,” Brad Furman’s latest is a piece of lurid pulp. But the Matthew McConaughey picture was clever and fun; “Runner Runner” isn’t. Partially that’s because it’s so reminiscent of the Jim Sturgess-Kevin Spacey casino-based thriller “21.” In fact, the similarity to “21” is so striking that it should really be titled “Rerunner Rerunner.” But that’s only the start of its problems.

Here Justin Timberlake, seeming a bit more at ease in front of the camera than he has in the past, plays Richie Furst, a Princeton grad student who, like the MIT undergrad Sturgess played, is strapped for tuition money. (He was once a Wall Street highflyer, but was a casualty of the 2008 meltdown.) His solution is to raise the cash by acting as an agent for on-line gambling sites (precisely how is never explained), which we’re told in a jumbled credit montage are increasingly popular on campus, but the scheme is quashed by the crusty old dean. Desperate Richie decides to try turning his remaining seventeen grand into big bucks by playing poker online himself, but he loses it all and, with the help of his math buddies, proves that the site cheated him.

Armed with the evidence, Richie doesn’t go to the cops but rather to Costa Rica, where the website’s founder Ivan Block (Ben Affleck) lives the life of Riley away from the tentacles of the federal government, bribing local officials to host him and his glitzy crew. Naïve Richie not only believes Block’s protestations that a few bad apples—since fired—were responsible for his loss, but is seduced by Ivan’s offer of a job as his aide-de-camp that will quickly bring him an eight-figure salary.

Soon Richie’s living the high life too, though threats from a hot-dog FBI agent (Anthony Mackie) who wants to turn him into an informant against Block cause him concern. In time, though, he comes to realize that Ivan’s a cold, calculating guy with a decidedly malevolent streak; rather than a misunderstood businessman, he’s knee-deep in bribery, strong-arm tactics and a willingness to sacrifice others to promote his own interests. The only question is whether Rebecca (Gemma Arterton), Block’s right-hand lady, is on the level when she takes a liking to Richie or is just a spy for the boss.

It turns out, of course, that Block is manipulating Richie for his own very nefarious purposes, just as Kevin Spacey did Sturgess in “21,” and the poor boy has to find a way out of the mess he’s gotten himself into—something made more difficult when Ivan gets the lad’s father (John Heard, looking convincingly dissolute) under his thumb. The last reel offers some contrived twists to end things on the proper fictional note of punishment for the guilty and exoneration of the relatively innocent.

But that Sting-like denouement symbolizes a basic problem with the entire movie: though it belabors some crushingly obvious points about the plan Furst concocts to save himself, overall it’s not successful in explaining how it all goes down. Similar blank spots occur throughout. We’re told that Block is scamming his customers, for instance, but it’s never made clear precisely how, except that he’s running a “Ponzi Scheme”—a phrase that’s basically a verbal MacGuffin. It probably would have been laborious to lay out how his operation actually works—after all, the details of the operation to beat the casino in “21” were rather exhausting—but surely we could have been given a better understanding of the process.

Moreover, though there are lots of supposed surprises in “Runner Runner” and plenty of characters involved in them, in the last analysis the plot isn’t much smarter than Richie is. It’s just a tale of an eager but immature fellow who’s taken in by an ostentatiously bad guy but then turns the tables on him. One longs for some of the cunning of “The Lincoln Lawyer,” but it never comes; the script just follows an inordinately predictable course to close just as you knew it would.

It doesn’t help matters that one of the leads is so lightweight. Timberlake evinces energy, but he remains a bland fellow, his reactions showing little depth. Affleck is a lot more fun, racing through Block’s rants with a cynical smirk and a gleam in his eye, and he certainly makes the character the sort of creep you can love to hate. But Arterton is given little to do but look pretty—which she does easily enough—while Mackey’s flamboyance doesn’t conceal the hollowness of the agent he’s playing. Nobody in the supporting cast, save for Heard, makes much of an impression.

But Puerto Rico does, standing in for Costa Rica and photographed by Mauro Fiore to look alternately alluring and threatening. (One can understand why Costa Rica itself would have demurred at hosting the production, since it’s portrayed as a seedbed of corruption and violence.) The remaining technical contributions are okay but unexceptional, with Jeff McEvoy’s editing sometimes going lax, and Chrisophe Beck’s score is nondescript.

The result is a picture one should run from, not toward.