Leng Feng is sent to solitary confinement as punishment, but is approached by Long Xiaoyun, the female commander of the legendary 'Wolf Warriors', an elite unit within the PLA tasked with simulating foreign tactics for the PLA to train against. Long Xiaoyun offers Leng Feng a place in the Wolf Warriors and he accepts, being airlifted to their training grounds the next day. The Wolf Warriors field leader lectures Leng Feng on the importance of teamwork to success.
Meanwhile in southeast Asia, crimelord Min Deng is apprehended by authorities but rescued by group of foreign mercenaries led by ex-US Navy SEAL 'Tom Cat' (Scott Adkins). It is revealed that Min Deng is the older brother of Wu Ji, the drug smuggler slain by Leng Feng in 2008. Min Deng re-hires Tom Cat and his group to assassinate Leng Feng, but warns them not to underestimate the strength and resolve of the People's Liberation Army.
The Wolf Warriors participate in a training exercise in a remote and uninhabited forested region on China's southern border. During the exercise, Tom Cat and his mercenaries ambush a Wolf Warrior squad, killing one of Leng Feng's comrades. Leng Feng and PLA helicopters pursue Tom Cat but he escapes, using graphite-powder weapons to deny airspace to PLA air support. Without quick-reaction air support to call on, PLA commanders cancel the training exercise and send a combined force of the Wolf Warriors and People's Liberation Army Special Operations Forces into the forest to apprehend Tom Cat and his mercenaries. While re-arming from helicopter-delivered supply drops, the Wolf Warriors are inspired by a speech from their commanders to defend the honour of China and avenge the death of their comrade.
The combined infantry force move into the forest but are delayed by multiple traps set by Tom Cat and pinned down by sniper fire from Assassin, Tom Cat's elite marksman. Leng Feng and the other soldiers cut down a tree with sheer firepower to create cover and Leng Feng sprints into the forest alone to flank Assassin, dodging his fire and managing to engage and kill him at point-blank range.
Meanwhile the rest of the PLA force engages Tom Cat's other mercenaries, who stage a fighting retreat but are eventually overwhelmed and killed one by one. At base, Long Xiaoyun and the other PLA commanders deduce that Ming Deng himself is also in the training area to take possession of a smuggled cache of biotechnology, which could allow the creation of a genetic weapon that could target Chinese people exclusively.
Leng Feng again pursues Tom Cat through the forest, who delays him with multiple traps including a land mine, which Leng Feng triggers but escapes from by digging a pit under the mine and jumping away from the blast. He eventually catches Tom Cat just before the marker delineating China's southern border. Both fighters empty their weapons at each other before engaging in close-quarters combat. Leng Feng, wounded and exhausted from the previous fights, is nearly defeated, but manages to kill Tom Cat with his own knife after Tom Cat mocks Leng Feng's patriotism.
Medical personnel from a PLA relief force arrive, but Leng Feng recognises the wrist tattoo of the medic that approaches him and realizes that they are Min Deng's men in PLA uniforms. He grabs a rifle and attacks them, eventually holding Min Deng himself at bayonet point on the very edge of the Chinese border. Min Deng's massive paramilitary force approaches from the other side of the border, but so do the rest of the Wolf Warriors and PLA soldiers. Min Deng's force retreats.
After the action, Commander Long Xiaoyun agrees to accompany Leng Feng for a drink.