In the weeks before Kima's arrival to Republic City, Mako had returned to duty as a detective in Lin's triad task force despite his injury. Much to his displeasure, though, he was partnered with his younger brother, Bolin.

The police force had their hands full investigating the triads ravaging the city, as the different factions engaged each other in turf wars over the land that was not destroyed during the invasion. When the Triple Threat Triad attacked the Creeping Crystals, Mako was among the officers who interfered. Having both arrested a triad member and loaded them into their vehicle, Mako and Bolin headed back to the temporarily police headquarters to start processing the criminals. During the ride back, Bolin engaged in small talk with Two Toed Ping, only to have his brother by gruffly correct him and placing emphasis on the temporary nature of their partnership. After they had arrived back at the station and finished booking their prisoners, Mako walked in on Lin's interrogation of Two Toed Ping about the identity of the Triple Threats' new leader, which was leading nowhere. He pulled her aside and suggested they trick Ping into believing that he had been identified by another triad member as the mastermind of the earlier attack on the Creeping Crystals in order to get Ping to talk. The ruse worked, and the two learned that the true mastermind had been Tokuga, a dangerous criminal whom they quickly bumped to the top of their most wanted list.

Sometime later, Mako and Bolin took a trip to Air Temple Island to visit Avatar Korra and their friend Asami for the first time since the women had returned from their vacation to the Spirit World. When Bolin asked how Korra and Asami's vacation had been, Mako noticed how strange they were acting and called them out on their behavior. But before they could say anything, Tenzin's eldest daughter Jinora's spiritual projection appeared to warn them about the ongoing attack of the Triple Threat Triad on the spirit portal. Mako asked her if a man fitting Tokuga's description was there, which Jinora confirmed, and Team Avatar quickly made their way over to the portal on a flying bison. Along the way, Mako informed the others that Tokuga was the Triple Threats' new leader and tried to contact the rest of the police force for assistance. He failed to connect, however, as the radio frequencies had been fickle ever since the creation of the portal, and warned his friends that they were on their own for the battle.

Once they had arrived, Mako sought out and challenged Tokuga, attacking him with his firebending in an attempt to arrest him only to have the nimble gang leader easily evade the blast and use his hook swords to launch Mako through the air. As he was about to finish Mako, Bolin came to the defense of his brother, forcing Tokuga to flee. Bolin helped his brother to his feet, but he felt downcast having been given the slip by Tokuga and he formally acknowledging their partnership as his brother comforted him.

Following the attack at the spirit portal, Mako and Bolin filed a report with the chief. As Lin finished reading, Mako added to Lin that he believed that the Triple Threats had been bought, and that Korra had a hunch it was Wonyong Keum. Lin listened to Mako, asking if he bought her "cockamamie" theory. He said he thought it was possible, and suggested that they bring Wonyong in for questioning. She refused, however, because Wonyong was powerful and well connected, making him difficult to get to. She told Mako he was not to bring Wonyong in unless he had hard evidence that the Triple Threats and the businessman were connected. As they left Lin's office, Bolin remarked to Mako that he guessed that the lead on Wonyong had been a dead end, but Mako didn't think so and suggested that the two of them should pay a visit to Two-Toed Ping.

Once they had reached his cell, Mako asked Ping if he had any idea of where the Triple Threats' new hideout was. Ping told him that they changed hideouts every few days, and that he had no idea where they were right now. Mako said that if he cooperated, they had be willing to get him some better accommodations for his jail cell. Ping insisted that he was being honest, and that Tokuga had no way of sending him messages through prison, so he had no idea where they were. Bolin remembered how, when they were kids, the Triple Threats had used them to move messages between Triad members, and suggested that maybe Tokuga was doing the same thing. Mako questioned Ping about the manner, and Ping nervously told him that maybe it was possible, which Mako took as a yes. As they walked away from Ping's cell, Mako told Bolin had displayed some good thinking, and would make a fine cop one day, to which Bolin replied that he had learned from the best.

After deciding to drive around the city, Bolin narrated the two driving around, featuring themselves saving Republic City from a shadowy evil force. Mako told him to stop because they were not filming a mover. Bolin said that maybe they should be, and proposed some titles, including "Good Cop, Bad Cop," and Mako said that he was assuming he was the bad cop in the scenario. Bolin haughtily remarked that he was naturally a charmer, and Mako was not talented enough to play off-type. Mako smugly remarked that Bolin was not either, and that Nuktuk was not far off from who Bolin was in real life, causing Bolin to defensively reply that Nuktuk had a lot of range, and questioned his brother about being cranky because his exes were dating each other. Mako defensively responded that he was fine, and that he thought it was great that the two were dating. Bolin said it did not seem like he was doing fine, but Mako interrupted him saying that it was Skoochy, the child they were looking for. Bolin to him not to change the subject, but Mako insisted that he had found Skoochy. Skoochy had noticed them, though, and darted away, which prompted Bolin to jump out of the car and follow him through one of the alleyways while Mako turned around and went through the other side. Bolin attempted to trap him through a rock wall, but Skoochy climbed over, only to run into Mako who grabbed him by his shirt and said it had been a while, and asked how he had been. Skoochy said he had been fine until the two of them had showed up, and asked what they wanted. Mako told the young triad member that he had heard that he might know where the Triple Threats' hideout was, but Skoochy said that he would not know because these days he was "living on the straight and narrow". Mako voiced his doubts about that and asked where Skoochy's clothes had come from, to which Skoochy replied that he had "found them". Bolin then angrily grabbed Skoochy and demanded he stop lying and answer Mako's questions, to both Skoochy and Mako's surprise. Mako told Bolin to go easy, and told Skoochy that he had been in his shoes once, and understood where he was coming from, but that at the end of the day he had a responsibility to the other people in Republic City, and that people could die if they did not find Tokuga. Skoochy mentioned that last he had heard the Triple Threats were in an abandoned warehouse by the docks but ran away saying that the two had not heard it from him. As Skoochy left, Bolin remarked to Mako that he would not have guessed it, but he was the bad cop after all. Mako ignored Bolin, saying that they had need to find Tokuga and to radio Lin for backup.

That night, Mako and many other police officers raided the abandoned warehouse. Lin lead the charge, checking to make sure it was full of people before invading. She had detected at least twelve inside using the same technique her mother had taught her, then commanding her men to head in. They headed down the stairs, and Lin kicked the door open only to realize the people were dummies. Mako ripped his cast off and yelled at everybody to leave just before the factory blew up. He used the best of his firebending ability to hold off the flames from the explosion, as Lin, Bolin, and the other officers fled the scene. They all left the building, as it collapsed behind them, all managing to survive without any major injuries. Mako apologized to Lin, and she said it was alright, Tokuga had simply been one step ahead of them. She commanded her officers to sweep the area for clues of where he was going, and Mako told Bolin they would not find anything, but that he needed to follow up on the lead on Wonyong. When Bolin reminded Mako of Lin's orders, Mako remarked that he did not care, Tokuga had just nearly killed them and he needed to be brought down using any lead.

Later, Mako and Bolin went to Keum Enterprises' headquarters to try and meet with Wonyong Keum. They went up to a receptionist's desk and requested to speak to Mr. Keum, but she turned them away, saying they would need an appointment. The two insisted that it was important police business, but two security guards appeared and begun to escort them out of the building. As they were leaving, one of the security guards asked if Wonyong was in any trouble, and mentioned that he had not been at work or at home in days. Mako questioned why they had not contacted the police since he had been missing, and they responded that Wonyong did not like the police being involved in his private affairs. Bolin and Mako came to the conclusion that Tokuga had been involved in his disappearance and left.