Anyone could be on “The Gong Show.” Practically anyone could host it. But not too many people could host it and then claim that in the entirety of their television career, they worked as an assassin for the CIA. Thankfully for filmgoers, Chuck Barris was one of those people. George Clooney chose to do the next most difficult thing by putting Barris’ story on the silver screen in his directorial debut, “Confessions of a Dangerous Mind.”

The film is based on Barris’ autobiography, which purports that he worked simultaneously as a television producer and CIA hit man. Barris is played in the film by longtime supporting actor Sam Rockwell, best known (if at all) from his parts in “Charlie’s Angels” and “The Green Mile.” The cast around him includes Clooney as Barris’ CIA boss, Drew Barrymore as his long-suffering would-be girlfriend and Julia Roberts in a middling role as a fellow killer. The script was penned by Charlie Kaufman, possibly the only writer more bizarre than Barris himself.

The film begins with Barris as a recluse in 1981, lamenting his life. He goes from being a network page to an NBC management trainee, before setting out on his own trying to create television shows, struggling, and being lured into the CIA, where he learns to kill in some bizarrely funny sequences.

After that point, the film starts to come unstuck in time, wandering back and forth from 1981 to 1968 and everywhere in between. He kills, produces “The Dating Game,” kills, and creates “The Gong Show.” The pattern is enough to make the film uproarious, but it wisely dials the hilarity down, going for chuckles rather than big laughs. It delivers with moderate frequency, knowing that the film is totally unbelievable, and yet less so than the book from which it came. While most critics debate whether it could possibly be true, it never seems to matter, even as former associates of Barris make cameos to tell what they think.

Though it ultimately becomes confusing, the constant positives for the film come in the performances of Rockwell and Barrymore. Rockwell offers what should be a starmaking performance, mastering the part of Barris to the point that his eyes alone are enough to do his acting, while Barrymore is solid with her part.

Roberts, on the other hand, seems to bring the story to a halt in several scenes, never quite mastering her role. Clooney simply shows up, does his part and moves on, wisely keeping himself far from the spotlight and poising it firmly on Rockwell.

Although Clooney’s directing is solid, influenced heavily by Steven Soderbergh, the film loses sight of its source and turns ordinary near its conclusion. The surprising cause is the downright ordinary screenwriting of Kaufman.

While “Confessions” is entertaining in spurts — particularly in some noteworthy celebrity cameos — in the end, it becomes average, trying to explain Barris rather than accepting him as Rockwell does. In the end, it becomes not the confession in Barris’ book, but a plea for understanding based on a bizarre childhood. Thankfully, Rockwell’s performance gets the script through some rocky moments and unnecessary sequences.

“Confessions of a Dangerous Mind” is certainly not for everyone, but for those dangerous minds who would trade places with Barris, it is worth the investment.