After the destruction of Asgard at the hands of the Ragnarok, Thanos attacks the space transporter where the Asgardians led by Thor escaped, he looks for the Teseractos that Loki has in his possession, which is nothing more than the space gem, one of the six gems of the infinity that Thanos seeks to complete the gauntlet and balance the destiny of the universe.
Heimdall in a last effort manages to send Hulk to the earth through the Bifrost, who lands abruptly in the New York Sanctuary temple as Burce Banner and is received by Dr. Stephen Strange and his faithful collaborator Wong; who warns that Thanos is on his way.
Doctor Strange locates Tony Stark, who are on a romantic walk in central park accompanied by his wife Pepper Potts; Stephen and Bruce asks Tony to accompany him to the temple to explain the situation.
Wong describes the power and function of the gems of the infinite, and how each one has its effect on the universe; Thanos has managed to get the power gem he stole from Xandar, and the space gem he obtained from the Teseractos; at that moment his lieutenants enter the earth aboard their spaceships, they must obtain the time gem and the gem of the mind that are protected by Doctor Strange and Vision respectively.
Ebony Maw and Black Darff attack New York to obtain the time gem hanging on Doctor Strange's neck, for them they will have to face Stephen, Wong, Iron Man and the young Spider-Man, who on the way to school is prevented from situation by its arachnid sense.
On the other side of the world, Wanda and Vision, who have the gem of their minds in their heads, live a romantic moment in the streets of Scotland, when they are suddenly ambushed by Midnight and Corvus Glaive, Thanos' trusted soldiers and have the mission of taking the gem of the infinite, both are very powerful and give a great fight to the point of almost defeating the heroes, who are rescued by the sudden appearance of Captain Steve Roger, Falcon and the agent Natasha Romanoff.
These lead Wanda and a poorly wounded Vision back to the Avengers operations center commanded by Rhodey, a war machine, where they must devise a plan to stop Thanos and prevent him from taking the vision gem.
Meanwhile in space, the Guardians of the Galaxy come to a distress signal issued by the ship where the Asgardians traveled, but when they leave hyperspace they realize that it is too late; Fortunately they manage to rescue Thor, who wanders in space, he tells the plans of Thanos to Quill and company which decide to divide into two groups, Thor, Rocket and Groot will travel to Nidavallir, while Peter, Gamora, Drax and Mantis go to Knowhere for the gem of reality.
Ebony Maw manages to capture Doctor Strange and takes him into space on his ship, Iron Man follows him while Spider-Man already tried to enter her, both manage to expel Maw into space and free Stephen, but they cannot divert the course of the ship and end up on the planet Titan, where they will meet Peter and his friends, who come from failure when trying to stop Thanos in Knowhere.
On earth, Captain Rogers moves the Vision to the only place with the right technology to save him, and where he will find old friends, they go to WAKANDA, they are received by King T`Challa and Bucky who they now call white wolf.
There they will prepare the most important battle in the history of mankind, try to stop the army sent by the evil Thanos and save life in the universe.