The DC dirge “Joker: Folie à Deux” is a sequel in search of meaning.

For nearly two and a half hours, director Todd Phillips' pathologically unnecessary film runs through so many possible reasons for existence.

But as “Deux” becomes increasingly disturbing, repulsive and strange on the hunt, it ultimately never finds a satisfying conclusion.

At first, the film tirelessly tries to drag out the story of Arthur Fleck, the mentally ill aspiring stand-up star who, in the last film, snatched and killed a late-night talk show host on live television.

Joaquin Phoenix won an Oscar for playing the traumatized loser who is essentially Robert De Niro in The King of Comedy, plus clown makeup. So let's milk it for all it's worth.

But the truth is, without Batman to fight, the crazed Gotham man is stranger than he lets on.

Arthur whispers aimlessly, stares at him, screams, curses the world and laughs creepily over and over again, without having anything to show for it. This time we don't care about him or him.

Since Arthur's static journey behind bars alone isn't substantial enough for a second chapter, “Deux” flirts with a spooky concert for Phoenix and Lady Gaga as further justification.

The pop star actress plays Harleen “Lee” Quinzel – also known as Harley Quinn – a troubled woman imprisoned at Arkham State Hospital who is in love with Arthur and his angry Joker persona.

He has become a cult hero since his rampage, and a TV movie about his crimes has given him legions of confused fans like Lee.

Phillips, clearly dreaming of working for MGM in the 1940s, somehow saw this as a logical opportunity for the pair to perform songs on the scale of a Broadway musical – some 15 in all.

The choice is reminiscent of a song by “Miss Saigon”: “Why, God, Why?”

As they almost escape Arkham, Gaga belts out “If My Friends Could See Me Now” from “Sweet Charity.”

When Arthur learns he will stand trial for his crimes – his lawyer plans to plead for split personality disorder – he sings “For Once in My Life” by Stevie Wonder.

As he falls violently in love with Lee, the lovestruck prisoner sings “Bewitched, Bothered and Bewildered” from “Pal Joey.”

I was worried and confused.

Because the ballads, duets and production numbers with ballroom dancing and tap dancing are terribly awkward and contribute nothing meaningful or valuable.

The sequences are not cheesy, insightful, emotionally powerful or mind-blowing. What are they? About three minutes each. I would never listen to any of these covers.

Actually, the reason “Folie à Deux” is coming to theaters is simple. The first film, intended as a one-off, unexpectedly grossed more than $1 billion at the global box office. So here's a visually lush addendum to the money heist.

Aside from the admittedly alluring aesthetic with pops of color popping through the grotesque grime, Phoenix and Gaga are pretty good and click effortlessly.

Both love playing psychopaths and are far more suited to a DC Comics institution than the Palace of Versailles or the House of Gucci. They can be disturbingly well deranged.

However, her material is thinner than Joaquin's after his disgusting physical transformation for the role.

Phillips' plot, which takes place almost entirely in a prison and a courthouse, amounts to a tension-free legal drama and a hackneyed serial killer romance.

“What's a nice guy like you doing in a place like this?” Lee's eye roll in the first line to Arthur disappears.

“I killed five people – one of them live on national television,” he replies matter-of-factly, finally discovering the comedic timing that had so eluded him.

The second half of “Deux,” starring the talented Harry Lawtey of “Industry” fame as Harvey Dent, is all about “Order in the courtroom!” “I object” and “Next witness!”

And I regret to inform you that there are even more pointless songs.

“The clown with his pants falling down / Or the dance dreaming of romance / Or the scene where the villain is mean – that's entertainment!” sings a dejected Arthur.

Perhaps. But it's not an exaggerated, regressive “Joker: Folie à Deux”.