Miracle at the Meadowlands III — the story of J.J. McCarthy’s home debut with the Giants — was missing the final page that would’ve made it a Hallmark movie instead of a soul-crushing drama.

Because of McCarthy’s fourth-quarter brilliance replacing a benched Jameis Winston, the Giants threatened to become the rare NFL team to win despite allowing 34 consecutive points … until McCarthy’s final pass Sunday fell incomplete in a 34-27 loss to the Saints at MetLife Stadium.

So the Giants (3-2-1) were left to ponder how their defense went from pitching a shutout over the first 28 minutes to allowing six scores on seven possessions to getting four fourth-quarter stops.

“Way too hot, way too cold,” safety Jason Pinnock told The Post. “We have to find out what’s lighting the match and what’s blowing the candle out. Because when it’s good, it’s really good. And when it’s bad, it’s really bad.”

The Giants pulled Winston after the second of his two interceptions led to the Saints scoring a touchdown to take a 34-10 lead with 11:36 to go.

If the Giants were waving the white flag with a 0.1 percent win probability — after many of the 82,905 fans had headed for the exits or booed or both — no one saw it.

“I’m not surprised because with the type of team we have, anything is possible,” Kayvon Thibodeaux told The Post after a fourth straight game was decided with less than 20 seconds on the clock. “But I definitely think we dropped the ball. There are no moral victories. We have to be cleaner as a team.”

McCarthy threw an interception on his fourth pass but then caught fire playing no-huddle offense. He led three touchdown drives and finished with the second-most fourth-quarter passing yards (243) by a non-starter over the past 25 seasons, according to ESPN.

“We have a shot if the clock’s not at zero, no matter what,” McCarthy said. “You just kind of felt the juice coming on the sideline — defense making plays, offense making plays — and things just came together a little too late.”

Faced with fourth-and-1 at the 14-yard line with 12 seconds to go, McCarthy scrambled and fired incomplete to the back of the end zone for Isaiah Likely. Malik Nabers broke open from the slot, but it would’ve required a cross-field throw.

It looked like Likely’s arm was restricted by Jonas Sanker’s coverage, and he popped up motioning for the officials to throw a flag.

Giants quarterback J.J. McCarthy (18) makes a long-yardage run late during the fourth quarter when the New York Giants played the New Orleans Saints Sunday, October 18, 2026 at MetLife Stadium. Robert Sabo for NY Post

Giants quarterback Jameis Winston (19) is sacked by New Orleans Saints linebacker Pete Werner (20) during the second quarter of an NFL football game at MetLife Stadium on Sunday, Oct. 18, 2026. Robert Sabo for NY Post

“I don’t really get into those,” Likely said. “I feel like I can make any play on the ball as long as I get my hands on it. You never want to leave it in the ref’s hands.”

Had the Giants scored, head coach John Harbaugh admitted he would’ve called for a 2-point conversion and tried to steal a win.

What Harbaugh wouldn’t say is whether Winston or McCarthy will start next Sunday against the Texans.

“He did a heck of a job given the circumstances and kind of desperation time,” Harbaugh said. “It’s different than normal football, but made some plays and got us back.”

New York Giants quarterback J.J. McCarthy (18) is sacked by New Orleans Saints cornerback Martin Emerson Jr. (22) during the second quarter of an NFL football game in East Rutherford, N.J., Sunday, Oct. 18, 2026. Bill Kostroun for NY Post

If the Giants, who remain atop the NFC East, do not make the playoffs, they will rue the final 83 seconds of the first half and first 159 seconds of the second half against the Saints.

A chance to be 4-0 at home for the first time since 2008 and extend an unbeaten streak to four games began to disappear when the Saints wiped out a 10-0 deficit by scoring 17 points and running 17 offensive plays between true offensive plays run by the Giants.

How does that happen?

Daniel Carlson kicked a 58-yard field goal — a gutsy call by head coach Kellen Moore considering Carlson already had missed from 55 — with 1:23 to go in the first half, and Charlie Jones fumbled the ensuing kickoff.

“Just have to be better,” Jones said. “Any time you have the ball in your hands, you just have to make sure at a minimum you’re handing it to the ref at the end of the play.”

Saints wide receiver Chris Olave (12) completes a reception under coverage by New York Giants cornerback Nic Jones (31) during the third quarter of an NFL football game at MetLife Stadium Robert Sabo for NY Post

And then the defense fell one play short of a goal-line stand, allowing a game-tying 2-yard touchdown pass to a wide-open Bryce Lance as decoy Chris Olave drew a double-team with one second remaining.

Quarterback Tyler Shough, who finished two spots ahead of Jaxson Dart in the 2025 Offensive Rookie of the Year vote, led the Saints on back-to-back touchdown drives to open the third quarter. He accounted for four touchdowns with his arm and legs.

“Personally, I think we got down on ourselves when we got down,” Thibodeaux said. “We have to keep believing. When you play defense, you have to stop the bleeding. We have to execute more in that middle eight minutes of the game.”

With Cam Skattebo limited to five snaps due to ball-security issues, the Giants were a one-dimensional offense.

Quarterback J.J. McCarthy (18) of the New York Giants reacts on the floor during the fourth quarter of a game against the New Orleans Saints in East Rutherford, N.J., Sunday, Oct. 18, 2026. Bill Kostroun for NY Post

Excluding Darnell Mooney’s 20-yard reverse, the rushing attack accounted for 14 carries for 17 yards through three quarters and led to Winston forcing throws.

“We have to figure it out between coaches and players how to get the run game going,” left tackle Andrew Thomas said, “because it’s unacceptable.”

Tyrone Tracy Jr. scored two touchdowns, Malik Nabers finished with 12 catches for 165 yards and Likely added six catches for 99 yards with a touchdown and a 2-point conversion in the rally from 24 points down.

Most of the damage was in the fourth quarter. And as fruitless as anything in Miracle at the Meadowlands I and II (losses to the Eagles in 1978 and 2010, respectively).

“If we play a little better, we wouldn’t even be in that situation,” Tracy said. “You wouldn’t even have to see that type of offense.”