The answer involves a plan worthy of The Joker himself. Sources say Warners will make an ambitious attempt to use Scorsese to bring Leonardo DiCaprio into the world of comic-book movies. Certainly, Scorsese’s involvement in The Joker film, which The Hangover filmmaker Todd Phillips would direct, could elevate and diversify the studio's contributions to the genre, creating the potential to make awards-worthy films such as Christopher Nolan's The Dark Knight trilogy.

There's no offer for DiCaprio, and sources say Scorsese's deal to produce isn't even done yet. The chances of landing DiCaprio could be slim to none. But the attempt in itself sends a signal to talent that Warners wants to hire serious filmmakers to make serious films.

This plan was not met with applause in all quarters: Insiders say Jared Leto, the actor who portrayed the Clown Prince of Crime in last summer's Suicide Squad and is slated to reprise the character not just for a sequel but for another spinoff movie (with DC villainess Harley Quinn), was caught off guard by the plans. Leto is said to have made his displeasure with the notion of multiple Jokers known to his CAA agents, and rival agency WME has been using the concern to court him.

Warner Bros. launched its DC Extended Universe to compete with Marvel Studios with 2013’s Man of Steel. The movies have included the poorly reviewed Batman v. Superman: Dawn of Justice and Suicide Squad, as well as this summer’s well-received Wonder Woman, which was seen as finally correcting a wobbly series. The movies have a through-line not just of stories but also actors, making them part of a superhero universe.

Now, however, Warners wants to branch off with stand-alone movies that are unconnected to that version of the DC world. The new movies will have non-traditional takes on the heroes and villains of DC, and hopefully, attract actors and filmmakers who don’t typically toil in the comic-book movie world. War for the Planet of the Apes director Matt Reeves is developing a Batman stand-alone that, according to sources, will not star Ben Affleck, who plays the caped crusader in the DC Universe movies (Warners and Affleck have denied he is being replaced). The plan is to launch a separate label for these projects to distinguish them from the rest of the DC films. (Warners executives are acutely aware of the risks of audience confusion.)

For Joker, which could be the initial entry for the label, sources say the studio and Phillips would want DiCaprio or another A-lister to play the character as a gritty crime boss in a Scorsese-esque Gotham underworld.

DiCaprio, 42, has become the most in-demand actor in Hollywood despite refusing to star in traditional franchise pictures. Instead, he has limited his collaborators to A-list directors of (generally) original screenplays, including James Cameron (Titanic), Christopher Nolan (Inception) and Alejandro G. Inarritu (The Revenant, for which he won his Oscar).

But his most frequent collaborator has been Scorsese. The duo has made five successful films together over two decades: The Aviator, Gangs of New York, The Departed, Shutter Island and The Wolf of Wall Street.

One conduit between Phillips and Scorsese/DiCaprio is actor Jonah Hill, who starred in Phillips’ War Dogs but worked with DiCaprio in Scorsese’s Wolf of Wall Street.

Reps for Warner Bros, DiCaprio, Leto and Scorsese declined to comment.