A timeline of the events of this movie:
http://marvelcinematicuniverse.wikia.com/wiki/2016
May 2, 2016
Captain America and Falcon get a lead on an ex-HYDRA agent in Lagos, who they believe might be the Winter Soldier.
Bringing Black Widow and Scarlet Witch, Captain America and Falcon leave the New Avengers Facility and fly to Lagos to apprehend the man they believe may be Barnes.
May 3, 2016
As they approach Lagos, Falcon receives further information on the ex-HYDRA agent, and find out that it is not Barnes, but rather Brock Rumlow.
Attack on the IFID Headquarters: Brock Rumlow, now "Crossbones", plans to steal a biological weapon from the Institute for Infectious Diseases in Lagos, Nigeria. Captain America hears about the planned attack and with the other Avengers start to search for Rumlow. Crossbones' mercenaries successfully enter the IFID Headquarters stealing the bio-weapon he was looking for. The Avengers pursue Crossbones' men taking out several of his mercenaries. Crossbones escapes, but not before entrusting the bio-weapon to one of his men. While Falcon, Scarlet Witch, and Black Widow set out to find the bio-weapon, Captain America confronts Crossbones. When he unmasks Rumlow, he begins to blame him for his injuries. Rumlow then mentions Bucky Barnes to distract Rogers, then he activates a suicide bomb intending to kill they both but Scarlet Witch manages to contain the explosion around Rumlow and tries to move the blast away but she accidentally moves the explosion too close to a nearby building before letting it go and inadvertently destroys part of the building, killing numerous civilians and several relief aid workers from Wakanda in the process.
President Matthew Ellis gives a speech where he communicates that the country will help the people affected on Lagos and that they will stand together after this accident.
Following the accident on Lagos, the Sokovia Accords are released.
May 4, 2016
Tony Stark gives a speech at MIT, using a virtual reality creation of his to show the students how he wished his last moments spent with his parents in 1991 had gone. He then funds all of their projects, but cuts the speech a little early when the teleprompter tells him to introduce Pepper Potts, causing Stark to get upset about the recent break-up he went through with Potts.
Backstage after the speech, Tony Stark is confronted by a grieving mother whose son was killed in the Avengers' battle with Ultron in Sokovia. She places the photo of her son on his chest, and tells him that she blames him for her son's death.
May 5, 2016
Greatly affected by his encounter with Spencer's mother, Miriam Sharpe, Stark signs the Sokovia Accords, believing that the Avengers need control and restriction to stop such disasters and tragic deaths from happening again.
June 4, 2016
In the night, Peggy Carter dies peacefully in her sleep.
June 5, 2016
In an interview, one month after the incident in Lagos, the king of Wakanda, T'Chaka, tells that he and his nation support the Sokovia Accords.[19]
As Steve Rogers consoles Wanda Maximoff saying that what happened in Lagos was not her fault, Vision them that Tony Stark and the Secretary of State are waiting in the board room of the facility.
The Avegers reunite with Ross
Thaddeus Ross speaks to the Avengers, while he shows them footage from New York, Washington, D.C., Sokovia and Lagos. He tells them that the United Nations has decided that the Avengers can no longer be allowed to operate privately so they have created the Sokovia Accords, believing it to be the best balance between the Avengers' desire to secure world peace and the world governments' concerns over the destructive repercussions of their interference. Ross tells them that they have three days to make up their minds before the signing of the Accords in Vienna. Before leaving the facility, Ross says that refusing to sign will be seen as an act of resignation.
Meanwhile in Cleveland, Helmut Zemo ambushes retired HYDRA General Vasily Karpov. Zemo hangs him upside down over a sink, slowly filling it up to torture him into giving him the information he needs about the mission of December 16th, 1991 as he finds the Winter Soldier Book, which contains the words used to trigger the Winter Soldier's conditioning. When Karpov persistently refuses to give him information, Zemo leaves him to drown.
The Avengers team is divided over the act; Stark supports government oversight because he feels that they need to be held responsible, whereas Rogers worries that the Avengers may be compromised if they come under the control of the United Nations. Vision realizes that there must be a causality between the increase in heroes and the increase in disasters, and so supports the Accords, along with Natasha Romanoff and James Rhodes. However, Sam Wilson and Wanda Maximoff disagree. During their debate about the Accords, Rogers receives a message informing him of the death of Peggy Carter.
June 8, 2016
Peggy Carter's funeral takes place in London. During the funeral, to Rogers' surprise Sharon Carter delivers a eulogy, in which she reveals that Peggy Carter was her aunt.
After the funeral, Natasha Romanoff hugs Rogers to console him and keep him company. They discuss the issues over the Accords, and Romanoff speaks about how it is important that despite their differences, the Avengers need to stay together. She then leaves to get on the flight to Vienna for the signing.
Bombing of the Vienna International Centre
Bombing of the Vienna International Centre: Arriving at the Vienna International Centre for the signing of the Accords, Romanoff meets T'Challa, son of T'Chaka and prince of Wakanda, who appreciates her signing the Accords. As the meeting is about to begin, a terrorist bomb hidden in a news van by Helmut Zemo goes off, destroying the building and killing King T'Chaka of Wakanda. Zemo then travels to Berlin.
Steve Rogers and Sharon Carter discuss Peggy on the way back from the wake after the funeral. They are interrupted by Sam Wilson who informs them about the Vienna bombing.
When facial scans from security footage seemingly reveal the culprit to be James Barnes, T'Challa vows revenge on Barnes for his father, telling Romanoff that he will kill him. Rogers then calls Romanoff, she tells him not to get involved, or he will be arrested for ignoring the Accords.
Secretly trying to help Rogers and Wilson, Carter hands them a file she has found from her work about the potential location of the Winter Soldier in Bucharest. Rogers and Wilson go after Barnes, hoping to bring him in before the government do.
June 9, 2016
In Bucharest, Barnes discovers that the news are blaming him for the bombing on United Nations in Vienna. But he knows that someone has framed him.
Capture of Winter Soldier: Captain America locates Barnes in his hideout apartment in Bucharest. As they talk, Falcon informs Rogers that the police are entering the building. Barnes prepares to make his escape but the police arrive so Rogers and he are forced to fight their way down the stairwell of the building. Barnes escapes from the building but he is suddenly attacked by a mysterious man in a black panther-like suit. The two fight on the roof before Barnes manages to make his way out to the streets. The chase continues now with Rogers trying to catch up with Black Panther as he pursues Barnes.
War Machine captures Captain America, Black Panther and Bucky Barnes
The chase is interrupted by War Machine who has arrived to arrest the three of them. The Black Panther unmasks himself, revealing himself to be T'Challa to Rogers and Rhodey's surprise. They are then flown to Berlin in custody.
At the New Avengers Facility, Vision cooks paprikash to try to lift Wanda Maximoff's spirits. But when Maximoff tries to leave, Vision moves to block her revealing that Tony Stark has told him to stop Maximoff from leaving.
Steve Rogers, Sam Wilson, Bucky Barnes and T'Challa arrive at the Joint Counter Terrorist Centre.
At the center, Barnes is taken to be seen by interrogator Theo Broussard as Stark sits down to speak with Rogers. During the conversation, Stark explains about what went wrong with his relationship with Pepper Potts, and Rogers sympathizes. Stark explains that he wants Rogers to sign, Rogers reluctantly accepts to sign but when Stark reveals that he is keeping Maximoff at the New Avengers Facility, the conversation gets heated for a brief amount of time, and Stark leaves.
Barnes' interrogation begins, but instead of being seen by Broussard, Helmut Zemo has got into the center pretending to be Broussard who was killed by him. Using the E.M.P. that he has built, Zemo cuts off the electricity supply in the center and leaving him able to speak to Barnes in private. Zemo brings out the Winter Soldier Book. He uses the key words to trigger Barnes' Winter Soldier conditioning again. Zemo forces Barnes to reveal him the mission report of December 16, 1991 and the HYDRA Siberian Facility before ordering Barnes to rip himself out of his bindings and break out of his cage, going on a rampage throughout the center. When Wilson and Rogers arrive, they manage to confront Zemo but Barnes attacks them. Barnes throws Rogers down an elevator shaft as Wilson pursues Zemo.
Bucky Barnes attacks Tony Stark
Escape from the Joint Counter Terrorist Centre: Rogers attempts to climb back up while Stark leads the fight against Barnes but he defeats him. Barnes also defeats Sharon Carter and Natasha Romanoff he then is forced to fight T'Challa however Barnes goes away from him and goes out to the helipad on top of the building. Rogers arrives to catch the helicopter stopping him from leaving. The Winter Soldier crashes the helicopter in an attempt to kill him, but he fails, and the two fall into the water below, where Barnes is knocked unconscious, and Rogers brings him to the surface.
Steve Rogers traps Bucky Barnes' metal arm in a vice in a local abandoned garage so as to stop him from escaping if he is still conditioned when he wakes
Helmut Zemo escapes from Wilson and moves forward with his plan, boarding a flight to Moscow.
When Barnes awakes he proves to Rogers that he is free of the conditioning by recounting to him small details about their childhood. Rogers asks about what wanted Zemo so Barnes reveals the existence of other 5 Winter Soldiers that HYDRA created after he retrieved a super soldier serum in 1991. He says that they had got out of HYDRA's control and had been put back into cryogenic freeze. Barnes tells them that he thinks Zemo will be looking they to reactivate them. Rogers and Wilson discuss what they should do next. While Rogers thinks they are out of luck, Wilson tells Rogers that he might know someone who can help.
After convincing Ross to leave him the work to capture Rogers, Stark and Romanoff decide to recruit T'Challa and Rhodey but Stark reveals her that he has someome else in mind. Stark flies his Quinjet to Queens as fast as possible, hoping to get the help of the relatively new spider-like vigilante who Stark is sure that is the secretly teenager Peter Parker.
Rogers contacts Clint Barton and asks him to help rescue Maximoff and arrange to pick up Scott Lang. Barton accepts.
Parker arrives at his home only to find Tony Stark in his apartment, already talking to his aunt. Stark tells him that he has won the grant he applied for, subtly letting him know that he should go along with what Stark says, despite not knowing what he is talking about. Stark then goes to Parker's room to discuss things further with him. In Parker's room, Stark explains to him that he knows he is the new vigilante of New York. But when Parker denies, Stark finds Parker's hidden costume so Parker explains to him about his powers saying that he has the reponsibility to protect people. Stark informs him that he needs his help and they have to go to Germany, Parker eventually agrees as Stark promises to make him a completely new costume.
Rescue of Wanda Maximoff: Barton causes an explosion outside the New Avengers Facility forcing Vision to briefly leave the compound so he can get away with Scarlet Witch. However, Maximoff initially refuses to leave giving Vision time to arrive in and fight Barton. Because of his far superior abilities, Vision defeats Barton. Maximoff then decides to use her own powers to restrain the synthetic being and throw him down through many floors and deep underground, allowing them plenty of time to escape. Barton then informs her that they have one more stop to make first.
Hawkeye then picks up Scott Lang, as Rogers and Wilson wanted, and him, Lang and Maximoff fly to Germany to meet with Rogers, Wilson and Barnes.