When each season of "Curb Your Enthusiasm" ends, executives at HBO, and fans of the show, wait in earnest for Larry David to decide when or if he wants to make another one. My belief is that the gig is too much fun for David to entirely walk away from, but for 2013 he passed on doing more "Curb" in favor of writing and starring in "Clear History," an HBO film that debuts Saturday night at 9.

As David explained to the Television Critics Association last month, "I was thinking about 'Curb' or thinking about doing a movie, and I thought, you know, perhaps it’s time I tried something else. So I decided to do the movie. It’s not like, 'Oh, I have these ideas that I can use on "Curb," but I want to do them in a movie.' Because I wasn’t I wasn’t thinking that way. I was thinking either of doing either one or the other, and I just thought it was time to try something else."

And "Clear History" is in some ways a departure for David. The cast mostly consists of stars with whom David hasn't worked before — including Jon Hamm, Kate Hudson, Amy Ryan, Eva Mendes, Danny McBride and Michael Keaton — and several of them with little or no experience at David's brand of improv comedy, though "Curb" fans will be happy to see both J.B. Smoove and Philip Baker Hall in small roles.  David isn't playing himself, but a character — Nathan Flomm, a marketing executive who becomes a national joke after he quits a job right before the company becomes absurdly profitable — with a complicated backstory and an attempt at an arc. And in pitting Nathan against his ex-boss Will Haney (Hamm) when the two men both wind up on Martha's Vineyard at the same time, "Clear History" purports to have a real plot.

But the movie also feels at time like an extended all-star jam episode of "Curb." Those are, perhaps not coincidentally, the best, and funniest parts of "Clear History."

David co-wrote the story with "Curb" veterans Alec Berg, Jeff Schaffer and David Mandel, and though director Greg Mottola is new to David's orbit, he's a veteran of directing comedies that leave room for improvisation.

David begins the movie looking unrecognizable in a flowing grey wig and beard to match — the better to justify a plot where no one on the Vineyard knows who he truly is once he starts wearing his (lack of) hair like Larry David — but Nathan Flomm is just as capable of getting hung up on minutiae as a certain wealthy "Seinfeld" creator we know well. He obsesses about the placement of electrical outlets ("What are they, like genitals? We have to hide them?"), and his dispute with Will deals with the name Will gave his son, and then the electric car the company is building ("Nobody's going to buy a car named Howard. It's like like naming a restaurant hepatitis!"). Even after he's spent a decade at the Vineyard, where he's the most beloved, likable guy on the island — an important character point, because he threatens the life he's built with this revenge plan — he still somehow winds up irritating the local diner owner by complaining about the common practice of leaving silverware on the tables. (Flomm, like David, is apparently a big germophobe.)

And when David is just being David, whether opposite a familiar co-star like Smoove or a more unexpected one like Hudson, "Clear History" is a lot of fun. Most of the improv newbies like Hamm and Hudson acquit themselves well in a company of masters (both of them are strong in separate scenes where they wind up, understandably, yelling at Nathan). And comedy veterans like Keaton (evoking Beetlejuice as a vengeful local handyman) and McBride (dryly amusing as the voice of reason in Nathan's inner circle) are clearly enjoying themselves. But some of the actors are either underused (Bill Hader essentially gets one joke to deliver, and Ryan is more notable as the subject of a running gag about the band Chicago than as someone who gets to be funny on her own) or misplaced (Mendes).

The revenge plot brings the characters together, but ultimately feels labored — this is the rare HBO movie that I wish was shorter — and doesn't come together as satisfyingly as your average "Curb" episode. 

But we're not going to get any "Curb" episodes until at least 2014 (if ever), and the funny parts of "Clear History" are good enough to act as an acceptable 100-minute substitute. David may have been arguing with himself about whether to do more "Curb" or make a movie; ultimately, he did both at once.

Alan Sepinwall may be reached at sepinwall@hitfix.com