There's terrific comic potential in the idea at the heart of Don Verdean, the latest shrug of a film from Jared and Jerusha Hess, the husband-wife writer-director team behind Napoleon Dynamite, Nacho Libre, and one that, for good reason, you haven't seen, Gentlemen Broncos. That idea: A fraud of a "biblical" archaeologist digs up holy "relics" for a fraud of a pastor to pass off as real to a congregation of eager believers. Better still: For farcical reasons, that archaeologist eventually must trick a mad billionaire by faking an Indiana Jones–style cave adventure.
That premise is priceless, but the Hesses do to it pretty much what Indy's Nazis had planned for the Ark of the Covenant: They make it into a bomb. Here, as always, they seem more engaged with curious, meaningless details than with character or jokes. You might not know, by the end, whether Sam Rockwell's archaeologist truly believes the nonsense he sells on his low-rent book tour, or whether he's actually as dismissive of his lovestruck assistant, Carol (Amy Ryan), as he seems. But you will know that when he drinks milk he winds up wearing it on his mustache.
Rockwell is charmless in a role that seems to be written that way. Verdean is a terrible lead for a farce, a shut-off blank we neither laugh at nor feel for. Not that the Hesses are whipping up a farce, exactly. Instead, this is another of their strange-accent buddy comedies. Jemaine Clement slowly takes over in the broad and baffling role of Boaz, a shifty Israeli huckster. He says junk like "How am I supposed to bring the money? Produce it from the anus?" It worked for the screenwriters.