None of the obits I've seen for Robert Stack has detailed the fascinating (to me) way in which he landed his signature role of Eliot Ness on The Untouchables. So here's the story as I always heard it…
The Untouchables started life as a two-part episode/pilot on an anthology series being produced for CBS by Desilu (i.e., Desi Arnaz and Lucille Ball). Arnaz cast Van Johnson in the role of Ness, in part because he figured he owed Van a favor. Van had been a co-star in Desi's one and only Broadway show, Too Many Girls. (He was also, oddly, Desi's understudy in the role of a Cuban football player. Was there ever an actor who looked less Cuban than Van Johnson?) Anyway, Johnson had done many favors for Desi, including just teaching him the ropes of performing in a stage musical, and Desi figured he owed him and that Van would make a good Ness.
The first of the two episodes was to start filming Monday morning. Saturday evening, Desi gets a call from Van's wife. Though Van was receiving very good pay for the job, she suddenly announced that she wanted it doubled, claiming that when they'd agreed to the fee they thought it was for one episode, not two. If Van doesn't get twice as much, she says, Van isn't showing up on Monday morning. Desi's Latin temper gets fired up. He knows it's a squeeze based on the assumption that he can't recast in one day, nor can he cancel the filming. Nevertheless, he tells her — in both Spanish and English — what he thinks of her, and sets out to find a new Ness. He flips through the Academy Players Directory, which is like a mug book for everyone in the Screen Actors Guild. He settles on Robert Stack and begins calling around town trying to locate him.
By now, it's well past midnight. Around 1:00 AM, he locates Stack's home number, phones there and gets the maid, who informs him that Stack is at a certain night club. Arnaz phones the night club, has Stack paged and asks him to go home and read some scripts that are being messengered to his doorstep. Stack, who barely knows Desi, is puzzled but he does as he's told. Around 3 AM, he phones Desi and tells him he's read the two scripts and thinks they're terrific. Arnaz offers him the same price Van Johnson was getting for the two episodes. Stack accepts and — 30 hours later — is on the set, shooting his first scene as Eliot Ness.
CBS doesn't much like the two episodes so they decline to order a series based on them. But the day after the first one airs, ABC calls up and buys the show, which runs for four years and makes Robert Stack very wealthy and very famous. And all because the Johnsons tried to squeeze an extra ten grand out of Ricky Ricardo.