The first thing about the movie you'll notice is that the budget must have been about fifty bucks. There's one set, a diner (the shack of the title) that has only about four customers, most of whom are spies. There's a small cast of characters, and you have to wonder why some of them are in the movie. Maybe they needed the work. Lee Marvin, on the other hand, must have jumped at the chance to play Slob. He's young, lean, mean, and crazy. He and Keenan Wynn (the owner of the diner) almost appear to be competing to see who can chew the most scenery. I think Marvin wins, but it's a close call. They're both having a great time, especially in the weight-lifting scene when they compare pecs and then ask Terry Moore to decide who has the best legs.
In the opening scene, Terry Moore is sunbathing on the beach. The camera lingers on her, and who can blame it. Down the beach is Marvin, who picks up a shell and puts it to his ear. I had a momentary disconnect here, because it looks exactly as if he's talking on a cell phone. He's much more interested in Moore than the shell, however, and he shows it in a way that you'd expect from somebody called Slob.
As for the plot, well, it involves Frank Lovejoy as a seashell collecting professor, spies, commies, a WWII vet who's lost his nerve, skin diving (sort of), and some of the most obvious foreshadowing ever put on film. It makes little, if any, sense. Many of the scenes are extended dialogs that occasionally seem as if they're going to last forever. There are many unintended laughs, and the intended comedy pretty much falls flat. Except for that weight-lifting scene. Yikes. I mean would you eat in a diner where the owner does bench presses on the counter?
I'm glad I finally got around to seeing Shack Out on 101. It was worth it just for Marvin's performance. He pretty much owns the screen in every scene he's in. And Terry Moore's not bad in a couple of scenes, either. Wynn gives it all he's got, which is considerable, but Lovejoy is a bit stolid.