“Revenge” season finale. (Adam Taylor/ABC)

So, that twist that we all hoped the “Revenge” writers would never use, but figured they probably would at some point if they ran out of ideas? Well, it appears that time has arrived. Not only did the writers gleefully exploit that certain twist in the third season finale on Sunday night, the ABC drama officially went off the deep end with a gruesome hour of television.

Hey, they need to keep viewers somehow since the show’s been renewed for a fourth season, and there’s no question that “Revenge” has been spinning its wheels for a couple seasons now. What started as one of ABC’s most intriguing dramas three years ago quickly spiraled into madness during its second season with confusing conspiracy theory plotlines. Then, the current season made some promising steps (getting rid of absurd stories and characters), and the season finale promised some big moments.

But then they reverted to the aforementioned twist: Yes, David Clarke is still alive. You know, the guy who was framed for a terrorist act and then “killed” in prison? The one whose death inspired his daughter to ruin many lives for three seasons, and inadvertently led to the death of many others? The guy around whom the entire show is based? Yeah. David Clarke is alive and kicking.

More accurately, alive and killing — our first glimpse of “Surprise! He’s alive!” came as David appeared mysteriously in the woods to stab his arch nemesis, Conrad Grayson (the rich guy who framed him for terrorism decades ago). Technically, it should have been a fitting, exciting moment; the audience was told David was allegedly stabbed in prison years ago. Instead, thanks to hints this cheap twist had been coming, it just came off as a silly ploy to extend an increasingly ridiculous plot.

This is exactly the kind of way to alienate an (increasingly disappearing) loyal audience: Make them feel like their viewing has been a waste of time. If David has always been alive, why has his daughter, Amanda Clarke-turned-Emily Thorne, dedicated her entire life to seeking justice for his death? It’s been the entire premise of the show since the very first moment of the pilot, and three seasons later, viewers will just feel cheated.

But the writers have thrown down the gauntlet, and there’s no going back. They really went all in. In fact, every thread of the season finale was creepier than the last, all of which will have disturbing repercussions next season. What was more unsettling: Queen of the Hamptons Victoria smothering Aiden to death with a pillow and then arranging his body to sit upright for his girlfriend, Emily, to find when she got home? The sight of a dead, bleeding call girl in Daniel’s bed? Emily’s revenge for Aiden’s death of smashing Victoria on the head with a shovel and having her committed to an insane asylum?

It’s hard to pick one moment. Either way, the “Revenge” writers and producers have put all their cards on the table: It’s a risky move, and one that could very easily (as things frequently do on this show) blow up in the worst possible way.