Train as an assassin and as an spy, Natalia Romanova battles spies around the world as Black Widow.
- Natalia Romanov/Black Widow - Scarlett Johansson
- Alexi Shostakov/Red Guardian - Kevin Dillon
- Ivan Petrovitch - Andrew Divoff
- Nick Fury - Samuel L. Jackson
- Damon Dran - Steve Howey
- James Barne/Winter Soldier - Sebastian Stan
- Yelena Belova/Black Widow - Olga Kurylenko
- Yuri Stalyenko - Ulrich Thomsen
- Robby Reynolds/Sentry - Bobby Campo
The film starts with Natalia Romanov as a child. At her home, in Russia, a fire soon starts and her parents are killed, but she is saved by Ivan Petrovitch, who then raises her as her surrogate father. A few years later, it is revealed that Natalia was also raised by the U.S.S.R.'s Black Widow Ops program with other young female orphans. She is trained in combat and espionage at the covert Red Room facility, where she is also biotechnologically and psyco-technologically enhanced, providing her with a long and youthful lifespan.
Many years later, Natalia is married to Soviet test pilot, Alexi Shostakov. One day, she is contacted by the Soviet military and told that her husband has died. Natalia is then trained as a secret agent.
After the events of the film Captain America 2, Natalia is now known as a soviet spy. She and Winter Soldier are sent to steal nuclear weapons by Yuri Stalyenko but as they are about to steal them, Natalia realises what she is doing is wrong and attacks Winter Soldier. The two battle and Winter Soldier almost kills Natalia but he leaves her for dead and takes the nuclear weapons back to Yuri Stalyenko. Natalia recovers after a while and returns to S.H.I.E.L.D. and becomes a S.H.I.E..L.D. agent again.
At the Soviet Military base, Winter Soldier asks what Yuri's plans are and he tells him that his plans are to start a nuclear war with America. Winter Soldier thinks about what he is doing and wonders if Natalia was right. As he thinks, a man named Damon Dran meets with Yuri Stalyenko. He begs Yuri not to do this and Yuri lies to him and tells him that if he bacomes a test subject for an experiment, he will not start a war. Damon excepts and becomes Indestructible Man and a new weapon of the Soviet Military.
Natalia's first misson back as a S.H.I.E.L.D. agent is to go to China and investigate some Soviet activity happening there. When she arrives there, she is confronted by Soviet agents. She is able to defeat them and is then confronted by someone who she thinks at first is Captain America, but soon finds out that this is a new foe. He is then revealed to be the Soviet Super Soldier Red Guardian. The two battle and, during the battle, Natalia is able to rip off his mask. She is then shocked to find out that the Red Guardian is her husband Alexi Shostakov. Red Guardian then takes back his mask and escapes the lab. He is then brought to the Soviet Military base by Soviet Agents.
Since Natalia is becoming more of a threat towards the Soviets, Yuri has a new Black Widow trained. Yelena Belova becomes the new Black Widow and believes that she must show that she is the true Black Widow by defeating Natalia. Yuri then sends Soviet agents to North America to lure in Natalia so that Yelena can defeat her.
Natalia is sent to investigate Soviet agent activity in North America and battles Soviet agents. She defeats them and is then attacked by Yelena. The engage in a fierce battle and Yelena sends Natalia over a cliff. Believing Natalia to be dead, Yelena leaves. After Yelena leaves, Natalia climbs back up the cliff face.
Believing Natalia to be out of the way, the Soviets continue with their plans. Yuri then sends Indestructable Man and Soviet agents to bring the nuclear wepons to the launching area however, the Soviets and Damon are confronted by Natalia who defeats the Soviets and kills Damon. Yuri and Yelena are watching over this and Yelena tells Yuri she was sure that she killed Natalia. Yuri told her that he expected this and was sending fake missles to the launch area to lure out Natalia. Yuri then has prisoner of the Raft Robby Reynolds freed and takes control of his mind. He then sends him to battle Natalia while him, Red Guardian, Yelena and Winter Soldier bring the missles to the launch site. As Natalia battles Sentry, Red Guardian starts to take control of himself and goes to help Natalia. Natalia is just about to be killed by Sentry when Red Guardian shows up and battles Sentry. During the battle, Red Guardian is able to snap Sentry out of Yuri's control. Sentry then agrees to help them.
Yuri, Yelena and Winter Soldier reach the launch site, which is an old Soviet base, and arm the nuclear missles. Natalia, Red Guardian and Sentry then arrive. The three are about to attack the Soviets when Yuri takes back control of Sentry's mind. Red Guardian battles Sentry while Natalia battles Yelena. Just as Yuri thinks he has succeeded in starting a nuclear war with America, he is shot in the back by Winter Soldier who tells him that his plan is wrong and that this needs to stop. Just before Yuri dies, he tells Winter Soldier that he is the only one who can stop the launch and tells Winter Soldier that he has just made sure that a nuclear war will take place. He also sets the base to self destruct as he dies. Winter Soldier then frees Sentry from Yuri's control and Yelena sees that Winter Soldier is right about the nuclear war. The five are then unsure about what to do and Red Guardian tells them to go and let him disarm the missles. Natalia then tells him that she disagrees with this and tells him that he will be caught in the self destruction of the base if he stays. Red Guardian then tells her that he knows and that she must let him make up for his past wrongs. The two then kiss and Natalia, Sentry, Winter Soldier and Yelena leave as Red Guardian disarms the missles and is killed in the explosion.
Back at the S.H.I.E.L.D. helicarrier, Nick Fury, Director of S.H.I.E.L.D., thanks Natalia for stoping the Soviets.
In a post-credits scene, Winter Soldier and Yelena are asked by Nick Fury to join S.H.I.E.L.D. and Sentry is asked by Nick Fury to join the Avengers.