The Avengers learned that the teens are held captive by the Purifiers,who are ordered by Bolivar Trask. As they rescues them,Ironman & Captain America realizes that the teens are mutants. The X-Men appears and save them. Later,Juggernaut broke free with the help of Quicksilver & Scarlet Witch.
Nick Fury meets with Professor X,who assures them that X-Men had their priorities with the Purifiers. Tony & Steve meets with Logan,who accused Steve for his disappearance while being captured. Later,Trask shows Senator Kelly his inventions,The Sentinels. He used the Mind Stone that encased Loki's scepter to activate one of them and it reprogrammed two more.
Charles tells Logan about the Purifiers taking half the mutants power. Tony tells Steve that if he knew,He could have joined them. Steve assures him that he already has a team. They soon learned that the Juggernaut attacks the Purifiers. Ironman,Captain America,Thor,Black Widow,& Hulk fought against him,Quicksilver,& Scarlet Witch. They quickly captures the twins,but Juggernaut escapes and report this to Magneto.
Professor X sent Wolverine,Cyclops,& the X-Men to locate the Purifiers. The Avengers got there before the X-Men. The two team fought eachother. Quicksilver & Scarlet Witch broke free and tells Professor X about the Purifiers' goal and later intervene,telling them about their real enemy.
As The two team confronted Trask & Kelly,The Sentinels are corrupted and kills Trask. They took down two Sentinels with Quicksilver & Scarlet Witch's help,but not before the X-Men member,Darwin was killed. Ironman,Captain America,& Wolverine manage to stop one more Sentinel,triggering the explosion. After Senator Kelly is arrested for conspiracy,The Avengers and the X-Men thanked eachother while Quicksilver & Scarlet Witch joined the Avengers.
Mid-Credits:
T'Challa:
Ororo Munroe to come see Wakanda,which she agrees.
Post-Credits:
The S.H.I.E.L.D. Agents gets all the pieces of the Sentinels to be put away. Unbeknownst to Fury & Maria Hill,The Sentinel's eyes glow red. Maria tells Fury that they found something on Hammer's file of a hidden base and something he has been working on. Meanwhile,Inside the lab is a Mechanical Silver Robot,whose eyes opened red.