What was the Second Red Scare? How and why did it grow so quickly? How did it affect the politics and society of the United States during the 1950s?

The Second Red Scare was a hysteria that led people to believe that communists had infiltrated the media and government. One of its primary leaders was Joseph McCarthy, who claimed to have information on several Washington communists. He was an important member of the House Un-American Activities Committee who investigated several organizations for having communist ties.
There were also investigations of Hollywood screenwriters who were accused of being communists. Many of them "pleaded the fifth" and would not incriminate others. By doing this, they were considered guilty even though they were exercising a constitutional right. The "Hollywood Ten" were a collection of screenwriters who were sent to prison and blacklisted from ever working in Hollywood again. Arthur Miller wrote The Crucible in 1953; while the play depicts the events of the Salem witch trials, the mounting hysteria and public accusations that surrounded the event closely parallel what happened in the Second Red Scare (which, in itself, was called a "witch hunt").
There were fears of Soviet takeover after WWII. US military officials claimed that it would take the Soviets at least twenty years to develop an atomic bomb. However, the Soviets—with the help of American spies and captured German scientists—dropped their first atomic bomb in 1949. The Rosenbergs were famously put on trial for selling secrets to the Soviet Union. Meanwhile, China, a recent American ally in the war against Japan, had recently become communist. It was becoming increasingly clear that the Soviet Union was going to be a permanent fixture in Eastern Europe.
The Second Red Scare grew as people became more afraid of Soviet takeover. Movies and magazines also fed into this; Time magazine placed McCarthy on its cover in 1954 at the height of his power. It was not until Eisenhower publicly confronted McCarthy that he was finally discredited. McCarthy never revealed information about specific communists. While there would be continuing suspicion of anything that looked like leftist thoughts throughout the Cold War, by the 1960s, the Second Red Scare was largely over.
http://content.time.com/time/covers/0,16641,19540308,00.html

https://www.history.com/topics/cold-war/huac

https://www.newyorker.com/magazine/1996/10/21/why-i-wrote-the-crucible