PLOT: Confused and a little crazy, the noirish plot concerns a series of messy murders and the exploits of a gay private dick (Val Kilmer) and his straight, bumbling sidekick (Robert Downey Jr.), who's got his eye on the femme fatale (Michelle Monaghan).

Many are chosen to die. Few escape their fate in Kiss Kiss, Bang Bang, a comic thriller that lucks into a preposterous, yet brilliant bit of casting.

With uber-producer Joel Silver behind him, rookie director Shane Black -- a veteran screenwriter who helped create Lethal Weapon -- put together Hollywood bad boys Val Kilmer and Robert Downey Jr.

Then he threw the match that ignited them.

It turned out to be a dynamite pairing, just as Mel Gibson and Danny Glover proved to have chemistry as buddies on patrol in the Lethal Weapon series.

In Kiss Kiss, Kilmer plays a fussy Los Angeles private eye who uses his gay sexual orientation as a weapon to manipulate the situation. The character is smart, sarcastic and witty.

No room for homophobia in this flick.

At Kilmer's side, and getting a kick out of the arrangement, is Downey. He plays a petty crook who runs from the cops, falls into a gig as an actor and then pretends to be a private dick. His character is stupid, blunt-funny and the object of Kilmer's ridicule.

In a plot that is too convoluted to follow and too ridiculous to explain, the Kilmer-Downey duo follows a trail of corpses around L.A. while trying not to end up dead themselves.

The $15-million movie, in part a roughhewn mockumentary, in part a slick homage to pulp writer Raymond Chandler, relies heavily on audiences enjoying the interplay of the two leads. There is a lot to like, because opposites attract. Kilmer uses a butch attitude and a radical cool to navigate their way; Downey is the fool, in a court jester kind of way.

Delicious support players include Corbin Bernsen in his super-sleaze mode. That's always fun.

A key component in the scenario is the femme fatale played by newcomer Michelle Monaghan, who has a gift. She can portray the sexy dumb blonde and yet emerge as a multi-layered character with real soul.

One bright if anal critic has noted that it makes no sense to have the 40-year-old Downey and the 29-year-old Monaghan together, considering they are supposed to have known each other as contemporaries in school (and we see some flashbacks with children of similar age playing the young versions of the characters).

But counting birthdays and examining the crow's feet around Downey's eyes assumes you even give a toss about such detail in this film.

Logic does not belong here. Instead, the film is all about mood and texture, about energy and propulsion, about sex and sass.

The Kiss Kiss is corporeal and sometimes venal. The Bang Bang is action. Then Black layers in wry humour. The result is a contemporary film noir that is pure pleasure.

BOTTOM LINE: Don't go if you want just a routine, conventional murder mystery. Do go if you want an adrenalized, sexy, comic film noir thriller that is as subversive as it gets in the City of Angels.

(This film is rated 14-A)