Renegade

Episode 69 of Robin & Batgirl: A New Adventure.
Nightwing, Batgirl, Blue Beetle and Huntress fought Bone-Crusher, Coyote, Silverback, and La Dama in an abandoned weapons factory. They prevented their attempt to sell weapons to the Black Market. Nightwing took on Bone Crusher, Batgirl took on Coyote, Huntress took on La Dama and Blue Beetle took on Silverback. After a few moments, the heroes defeated the villains and now the policemen came and sent them to jail. The weapons factory was left abandoned, for now. 
The next day, in the headquarters, Nightwing woke up, then sneaked into his wardrobe. He changed his outfit into a much cooler one. He is now "Renegade". He monitored Deathstroke's hideout. He used the surveillance camera to look at what Deathstroke is up to.
"I am just planning to have Washington D.C. erased from the States. I shall create a fusion grenade to blow this small state up", Deathstroke said.
"I gotta do this quick", Renegade said.
But Batgirl came and said, "Hey Nightwing,where are you?".
He hid behind the Batmobile. Batgirl searched for him in the main room of their hideout, but she didn't see him, because he was hanging at the ceiling. Later,when Batgirl went to her room, Renegade now went outside and used the R-Mobile. He went to the car facilities center in Downtown Gotham and demanded the repairmen to have his mobile improved. They declined. Renegade threatened them with a knife. Because of fear, the repairmen were forced and improved his engines, wheels, and the interior of his car. Now after he had his car improved Renegade rode on it and went to Deathstroke's hideout. He located it using his GPS. He entered it. Then he got surrounded by Ninjas.
"Oh my, I'm in trouble", he said.
He was beaten down at first but he fought back and took all of those down. He hacked the control buttons of the elevator and used it to go to the second floor of Deathstroke's hideout. There, he became much more careful not to be noticed by Ninjas. Meanwhile Batgirl went to the Batcave and asked Alfred if they seen Nightwing.
"I haven't, but we can take a look at the monitor",Alfred said.
"Where is Batman anyway?", Batgirl asked.
"He was thwarting Babyface's tomfoolery along with Wonder Woman", Alfred said.
Meanwhile, when Renegade was about to fall down at the floor while hanging from the pipes, the ninjas saw him but he teleported himself out of trouble with his utility belt. He teleported to the elevator. He now reached the third floor, where Deathstroke was creating the fusion grenade. He hid behind the machines so he cannot be noticed by the Ninjas and robots.
He heard from Deathstroke, "Deadshot, assure me that the heroes of Gotham are captured. They would watch themselves fail and watch Washington destroyed".
Deadshot said "Yes master". 
"Oh no", Renegade said, peeping behind large machines.
Renegade teleported back to the headquarters. Then, Batgirl saw him and hugged him, then she slapped him.
"What was that for?", Nightwing said.
"Where have you been all this time? Batman and I have been looking for you the whole time", she said.
"I just had a joy ride, gee. But, Deadshot was tasked by Deathstroke to take the three of us down. Then Deathstroke will activate will activate the fusion grenade in Washington D.C. then it will go boom", Nightwing said.
"What? Oh please. Please tell me you're joking", she said.
"It's real", he said seriously.
At afternoon, Nightwing disappeared again. He once again became Renegade. Now Batgirl spread the news to Batman and Wonder Woman.
"No worries, we've got Washington covered", Batman said.
Now, they rode the Batmobile and went to Washington D.C.
"Nightwing's kept me bothered these past few days. Why does he always disappear?", Batgirl said.
"Maybe he has a secret", Batman said.
"Oh, you must right. I'll do my best to discover it", Batgirl said.
Meanwhile Renegade was again in Deathstroke's hideout. Everything is cleared. Deathstroke sent all his minions in Washington D.C. leaving no one to secure his hideout. Sneaking has became easier for Renegade. He saw Deathstroke open a portal and when he was about to deliver the fusion grenade there, he threw a sharp disk at Deathstroke's hand. They fought.
"I don't have time for this!", Deathstroke shouted.
He kicked Renegade so hard he lost consciousness. Now Deathstroke went inside the portal with his fusion grenade. Meanwhile, Batgirl, Batman and Wonder Woman are fighting ninjas and robots. Deathstroke was hiding behind the bushes, where he was operating the fusion grenade. Batman, Batgirl, and Wonder Woman defeated all the ninjas and robots. But, Deadshot knocked them down with his blaster with just one shot. He now tied them with a rope. Meanwhile, Renegade regains consciousness and teleports back to the headquarters. He changed his costume to Nightwing. He now rode the R-Mobile to go to Washington. He saw the three heroes tied up together. 
He called Deadshot and said, "Hey, Deadshot. It's time we settle this one for good".
They fought. Nightwing evaded all the blasts then he got kicked. But he rose up and threw birdarang on his blaster. Deadshot shot laser at him using his eye, then finally Nightwing took him down using his pole. He freed the others. Then, Deathstroke appeared.
"You've got 12 minutes left or this city will go boom", he said.
Nightwing said, "Batman, Batgirl, Wonder Woman, go find the grenade in the bushes. Deathstroke is mine!!".
Now Deathstroke and Nightwing fought in hand to hand combat. They were evenly matched. But later Deathstroke took him down and now entered a portal back to his hideout. Now, he helped the others in finding the fusion grenade, but they already found it and they were trying to deactivate it, but they can't. They only had 2 minutes left. Then Nightwing came. He knew its control buttons because he was there when Deathstroke was creating it. At 10 seconds left, he finally deactivated it and turned it off. 
Later a portal appeared and Deathstroke emerged saying, "NO!! You'll pay for this insolence of yours one day, all of you!".
"You're the one who is insolent", Nightwing said. 
He kicked and knocked him down, then tied him in a rope. The police came and arrested Deathstroke and Deadshot. Now Wonder Woman said goodbye and flew away. The three rode the Batmobile going to the Batcave. 
Now Batgirl asked, "Nightwing answer me. Why have you been disappearing these past few days?".
He answered, "Oh, I... spied on Deathstroke, using the identity of Renegade. I infiltrated Deathstroke's hideout, and found out he was creating a fusion grenade. I spied on him while he was creating it".
"Good job, Nightwing. So that's why you knew how to deactivate it", Batman said.
"We are glad to see you at the right time. So you're actually doing your job. That's why I love you", Batgirl said. Nightwing blushed.
"I'm sorry if I made you two worry. I promise I won't do that again", he said.
"You're forgiven", Batman and Batgirl said.
Characters:Nightwing/Renegade,Batgirl,Blue Beetle,Huntress,Batman,Alfred,Wonder Woman,Police
Villains:Bone-Crusher,Coyote,Silverback,La Dama,Babyface,Babyface's Henchmen,Ninjas,Robots,Deadshot,Deathstroke
Trivia
* This episode is based on the Teen Titans episode "Masks",where Robin uses the identity of Red X to infiltrate Deathstroke.
* In case you don't what Renegade looks like,he looks the same as Nightwing's costume except the bird on his chest and back is color red and other parts are colored crimson.
* This episode has the longest plot in the whole Robin & Batgirl: A New Adventure.
* In the comics,Renegade was actually a villain who worked for Deathstroke.