The Hollywood career of Robert Downey Jr. has been something of a Biblical experience. Looked at in a certain way, you rarely see so much begatting in one lifetime. Young stardom begat an early Oscar nom. Success begat addiction. Addiction begat arrests. Which begat an indie film resurrection. Which begat critical appreciation. Which has now begat a return to stardom. This summer, his career finally walked completely out of its tomb.

So in this summer of his resurrection, can the dead-and-risen Downey save another film? He’s already saved one, breathing life into the otherwise rusted lungs of Iron Man (The intensity of The Dark Knight makes Iron Man seem like The Stay-Puft Marshmallow Man.). Can he do the same trick twice? His cool, delicious patter nearly lifts Tropic Thunder from the dead. But close doesn’t count in rising from the grave.

It’s a strange irony that Downey’s character is the one named (Keith) Lazarus. It’s the rest of the film that seems leprous. It feels like limbs are missing. Nipped of its intended comical punch, Tropic Thunder is a disappointingly flat take on Hollywood excess.

Lazarus is one of a set of actors working on a doomed Vietnam War production, a film gone spectacularly awry called Tropic Thunder. He plays opposite Tugg Speedman (Ben Stiller), an action star in desperate need of a hit. Speedman’s career is in rehab after his recent role as Simple Jack, an idiot farmboy with a Howdy Doody overbite. (This role will inspire Downey’s hilariously offensive “Never go full retard” riff.)

Downey, in contrast, plays the ultimate method actor. He’s the type of performer whose roles get underneath his skin. This time that means literally. In order to play a black American soldier, Lazarus has his skin darkened for the role. He continues to pretend that he is black even when the camera isn’t rolling. That doesn’t sit well with the cast’s true-to-life African-American (Brandon T. Jackson).

The film’s in-over-his-head director (Steve Coogan) decides to make things more authentic by flying the cast deep into the jungle. There, they stumble upon a real-life, well-armed drug cartel, who mistake them for DEA agents. Soon, the actors are forced to play Platoon for real.

The biggest disappointment is the film’s unappealingly jokey tone. Think what you will about The Pineapple Express; its satire is fanatically dug in, betraying little sense of self-consciousness. Conversely, Tropic Thunder doesn’t feel like it has worn in its shoes. It plays much too much like sketch comedy. That starts with its lead, co-writer, and director – Stiller – whose clowning always feels like it takes place independent of the millieu.

So I have one question about the performance of Jack Black. Who decided that Jack Black is funny? He isn’t funny. Not directly. He’s most funny when he isn’t funny but thinks he is. Jack Black without the irony of being Jack Black isn’t Jack Black. This, of course, sounds exactly like the sort of rant that Lazarus would go on in the film.

An unrecognizable Tom Cruise has a tasty little turn as a film producer in need of anger management, the best thing he’s done in years. Beyond that, the film mainly chronicles Downey’s talent and versatility. When Lazarus finally removes the make-up and fake hair, it’s not Robert Downey underneath; it’s just another mask, another tone, another film, and another layer of character. It’s a chameleon’s performance of the most stealthy kind.