Even before The First Avenger had been released, Marvel was planning the sequel. Christopher Markus and Stephen McFeely were annouced as writers for the movie. Plans for the movie changed, especially around Thor - The Dark World, but Disney announced that Captain America - The Winter Soldier would be released in May 2014.
Going for a decidedly more grounded in reality spy fiction, The Winter Solider starts us off 2 years after the Avengers movie. Steve is adapting to life in the modern day. In training, he meets with Sam Wilson. Steve is now part of S.H.I.E.L.D.'s new counter terrorist taskforce by the name of S.T.R.I.K.E and he's called on an all important mission. The mission goes smoothly, even as Steve finds out that Widow was on another mission to get information from the ship's database. Rogers returns to base to confront Fury about it, but is told about Project Insight, a new project that links 3 helicarriers to a network of satellites which is intended to be used to preemptively eliminate threats. Fury tries to get the project delayed.
However, when going to meet with Maria Hill, Fury is attacked by mercenaries under the employ of The Winter Soldier. Fury is wounded and escapes towards Steve's apartment. Fury hands Steve the flash drive to keep safe, but is shot by the Winter Soldier. Fury is evacuated and later dies in surgery. Now branded a fugitive, Rogers goes on the run with Widow. Decoding the flash drive sends them to Camp Leigh in New Jersey, where they find a hidden S.H.I.E.L.D. bunker. Going inside, they activate the consciousness of Arnim Zola, now trapped inside a computer. He explains that Hydra and S.H.I.E.L.D. are connected. Hydra operate within it's ranks to sow global chaos, to which the public will surrender their freedoms to defeat. They narrowly escape the bunker as it's destroyed by a S.H.I.E.L.D. missile.
Rogers and Widow enlist the help of Sam Wilson, a former Pararescueman, They work out that Jasper Sitwell is the mole. They confront him about his leaks, but he's assassinated by Winter Soldier. Rogers, Widow and Wilson give chase and get into a fight with Winter Soldier and his Mercenaries. Rogers works out that the Winter Soldier is his best friend, Bucky, who was supposedly killed in WW2. Maria Hill arrives and extracts them to a safe house, where they find that Fury faked his death. They come up with a plan to sabotage the Helicarriers by swapping out their control chips.
The World Security Council arrives at the Triskelion to witness the launch of Project Insight. They're unaware that Hydra controls the helicarriers and has the guns aimed at the world. Rogers broadcasts Hydra's plan to the world. Fury forces Alexander Pierce to unlock the S.H.I.E.L.D. database so Widow and publish the secrets to the internet. Cap then begins his assault on the helicarriers. He succeeds with two without trouble, but then meets Winter Soldier on the third. After a brief fight, Cap is able to swap the final chip. He tries to convince Winter Soldier that he is Bucky, refusing to fight him. Hill takes command of the three helicarriers and commands them to attack each other, destroying them. In this, an unconcious Cap falls into the Potomac River. He's saved by the Winter Soldier, who places him on the shore before walking off. Widow appears before the Senate Sub-Committee. Fury heads off to Eastern Europe to round up Hydra. Rogers and Wilson agree to go after Winter Soldier. In the mid credits scene, Baron Strucker investigates an odd scepter. The camera pans to two cells, one with a subject with super speed, the other with telekentic powers. The post credits scene shows Winter Soldier in the Smithsonian, looking at a Bucky memorial
The Russo Brothers followed up with a great movie. It takes spy fiction and turns it on it's head. It shows the world is grey, not black and white as Cap would usually see it. There;s now a "who do you trust?" element to the movie. The Winter Soldier is available on all formats