The Attack on Vision was an ambush staged by the Black Order to obtain the Mind Stone embedded in Vision's forehead, who was only saved by the unexpected arrival of Steve Rogers, Black Widow, and Falcon, who had been warned by Bruce Banner of the incoming danger.
While off the grid, Maximoff and her romantic interest, Vision forged deals with their respective teammates to be able to secretly reunite with each other. They would be allowed to periodically have secret meetings together in order to blossom their growing relationship, on the condition that they return to their teammates after their conclusions. During these meetings, Vision would use his powers to assume a human form to visit her, turning off his tracker so his, and Maximoff's location, could not be found.
Roughly two years after the Avengers Civil War, on his quest to retrieve the six Infinity Stones, the intergalactic warlord Thanos tasked the Black Order with retrieving the Mind and Time Stones on Earth, placing a target on Vision's head. Ebony Maw and Cull Obsidian left to retrieve the Time Stone from the New York Sanctum, while Proxima Midnight and Corvus Glaive were en route to take the Mind Stone from Vision.
During the events of the attack on New York, Bruce Banner determined that Vision would be one of Thanos' next targets, but was notified by Tony Stark that Vision had shut off his tracker two weeks earlier, and had gone missing. Realizing that only the rogue Steve Rogers could possibly locate him, Stark reluctantly attempted to call Rogers on the burner phone he had left for him, only to be interrupted by the arrival of the Black Order. After the conclusion of the attack, Banner managed to locate the discarded phone and call Rogers himself, warning him of the threat on Vision's life.
Vision and Maximoff were having another secret meeting, hiding out in a hotel room in Edinburgh. In the middle of the night, Vision looked over the window and started to feel pain from the Mind Stone embedded in his forehead. Maximoff woke up and noticed Vision's concern, he told her that the Stone was desperately attempted to communicate with him, and warn him of the coming threat of Thanos. Maximoff tried to use her abilities to mentally interface with the Stone, but felt nothing but Vision himself.
Wanda Maximoff and Vision were walking through the empty, late-night streets of Edinburgh. Maximoff began to suggest train schedules to allow him to return to his waiting teammates, only for Vision to suddenly refuse. Vision proposed that he stay permanently with Maximoff instead, finally willing to fully commit to a relationship with her, to which Maximoff agreed, despite having to leave their fellow teammates behind.
However, before they could discuss further, Maximoff noticed a news report about an alien attack on New York, resulting in the disappearance of Vision's fellow Avenger, Tony Stark. Vision, feeling guilt due to not being present to help the battle, reluctantly changed his mind, telling Maximoff that he had to leave and help. Maximoff was reluctant to let him go, fearing for his safety.
Before Vision could answer, he was suddenly impaled from behind by Corvus Glaive, involuntarily forcing him back to his original android form. Before Maximoff could aid him, she was blasted away into a nearby shop by a shot from Proxima Midnight, allowing Glaive to begin forcibly prying the Mind Stone from the weakened Vision's forehead. However, before he could do so, Maximoff returned, throwing the Black Order away with her powers, and carry Vision and herself through the air to another street, away from the invaders.
Vision realized that the wound had disrupted his ability to control his density, as Maximoff attempted to use her abilities to heal the wound. Before she could finish, they were soon attacked again in a renewed assault by Glaive. Pushing Maximoff to safety, Vision grabbed Glaive and flew him across the city, smashing the alien into buildings, while Maximoff faced the attacking Midnight on the ground in close combat. Glaive offered to spare Maximoff's life in exchange for the Stone, only for an enraged Vision to ram him onto a church roof.
As Midnight and Maximoff dueled on the street below, Vision began to gain the upper hand, pummeling Glaive repeatedly. However, as Vision fired a blast from the Mind Stone at Glaive, it was deflected using the blade of his weapon, destroying a truck near the two combatants on the street. Glaive redirected the beam to hit Vision, stunning the android, and allowing Glaive to continue to forcibly and painfully extract the Stone. Maximoff, hearing Vision's screams, incapacitated Midnight by bending backwards and throwing her into the destroyed truck, before flying to the cathedral roof to rescue Vision from Glaive, blasting the latter away. Maximoff attempted to fly herself and Vision to safety, only to be blasted out of the air by a recovered Midnight, causing the two to fall into a nearby train station.
Vision, severely wounded, pleaded with Maximoff to leave, but she refused to leave him behind, preparing to make her final stand against the Black Order. However, they were interrupted, as Midnight spotted a new figure appearing behind a passing train, hidden in shadows. Midnight immediately threw her spear at the figure, only for the figure to effortlessly catch it, much to her shock. The figure stepped out of the shadows, revealing himself as Steve Rogers, who had been called by Bruce Banner to locate and protect Vision, alongside Natasha Romanoff and Sam Wilson.
In a coordinated attack, the three rogue Avengers engaged the Black Order, attacking together and even using their own weapons against them. With Wilson knocking Midnight away, Romanoff managed to use Midnight's spear to severely injure Glaive, while Rogers retrieved Glaive's weapon. Midnight summoned her spear from Romanoff and attempted to kill the Avenger, only to be blocked by Rogers. The two Avengers managed to overpower and disarm Midnight in a brief melee duel, before Wilson flew in and knocked her down, cornering them.
While Wilson held both Midnight and Glaive at gunpoint, Romanoff threatened to kill them. Infuriated, Midnight countered, claiming they would never get the chance, before the two retreated to their waiting Q-Ship and fled to orbit to nurse their wounds, taking their weapons with them.
The three Avengers took the injured Vision and Wanda Maximoff back to their stolen Quinjet to plan their next move. While Natasha Romanoff berated Maximoff for not regularly keeping in touch due to their romantic meetings, Steve Rogers decided to finally return to the New Avengers Facility, knowing that the coming threat was bigger than anything they have previously faced.
The team arrived at the compound to find James Rhodes talking to Secretary of State Thaddeus Ross over a call. Ross ordered Rhodes to arrest them, only for the Avenger to ignore the Secretary, disconnect the call, and welcome his teammates with open arms.
They were also greeted by the arrival of Bruce Banner, who had been gone for a few years, and who brought tidings of the coming of Thanos. Discussing their next move, the Avengers realized that the invaders would return again, and would not stop until they retrieved the Mind Stone. Vision proposed that Maximoff's powers, being a creation of the Mind Stone, would be the only thing capable of destroying it, and thus offered to sacrifice himself to prevent the Stone from falling into Thanos's hands.
Unwilling to sacrifice one of their own needlessly, Banner suggested removing the Stone from Vision in order to save him, but noted that he himself is unable to perform such a difficult operation. Rogers proposed moving Vision to Wakanda, the only place with the technology advanced enough and capable of executing such a complex task.