TV’s coolest funnyman is also, by this account, its most insecure. While at NBC Letterman all but flagellated himself after a mediocre performance; loud crashing noises would emanate from behind his locked office door. “I hate myself, " he once confided to a show guest. When CBS came courting, Letterman’s anxieties and indecision took a nail-gnawing toll on everyone involved. Only after Johnny Carson told him what he would do did Letterman finally cut the talk and take the walk.

Huggy-bearish Jay Leno, on the other hand, harbors the competitiveness of Eve Harrington. To save his “Tonight” throne, Leno tirelessly lobbied NBC affiliates and advertisers, then relayed their pledges of support to the press. Leno even hid in an NBC storage room to eavesdrop on a network conference call to debate his fate, carefully noting who spoke against him.

Now we know why Michael Ovitz reportedly runs Hollywood. At his first meeting with Letterman, the omnipotent CAA chairman promised the seemingly impossible. Dave would see every network bidding for his services. He would become the next Carson, the new king of the night. Later that day, a dazzled Letterman kept babbling, “I’ve been to see the Godfather!” Actually, Ovitz is scarier.

Instead of hooking onto one late-night star and holding fast, NBC president Robert Wright tried to have it both ways. Wright authorized a secret, last-second offer: Dave could have Jay’s job, but only 17 months later when the latter’s contract expired. After word of the offer leaked to the press, NBC vehemently denied its existence, only to see the story later confirmed by those in the know. The upshot: NBC embarrassed itself, humiliated Leno and still lost Letterman.

The book’s most bizarre character is Helen Kushnick, who ran Leno’s career for 17 years before becoming producer of “Tonight.” Besides berating her client in public (“Go write your f — ing jokes”), the hyper-volatile Kushnick, says Carter, alienated powerful talent bookers, blackballed stars, planted phony stories and raged at NBC executives before finally walking the plank. Naturally, Kushnick will be played by Faye Dunaway in the mini-series.

Carter, who’s a better reporter than analyst, doesn’t try to draw any conclusions, let alone a moral. Here are a couple of possibilities. (1) What’s happening in TV is more entertaining than what’s on it. (2) As in the real jungle, it takes the depths of the night to bring out the truly strange.