He provided contemporaneous accounts of major events and political figures such as the Hindenburg disaster, Alger Hiss, Barry Goldwater, the Cuban Missile Crisis, and the Watergate scandal.

In 1967, Cook successfully sued the religious broadcaster WGCB for maligning him in a landmark case that led the United States Supreme Court in 1969 to uphold the fairness doctrine.

[4] Living in an isolated New Jersey area with few friends, he immersed himself in his father's library of books and decided at age fifteen he wanted to be a writer:But how did one get started in this field?

In addition to his duties as a cub reporter, he soon became known as a good rewrite man who could "transform a flood of chaotic incoming notes into readable, vigorous copy".

[6][7] Among his early assignments, he reported on the burning of the Morro Castle ocean liner off the coast of Long Beach Island in September 1934.

[9] Having witnessed the airship flying overhead, he wrote a story about its anticipated safe arrival at nearby Lakehurst Naval Air Station.

Gleason was looking into possible corruption in how Moses was implementing the U.S. Housing Act of 1949, specifically "Title I: Slum Clearance & Community Development & Redevelopment".

Fitzgerald asked Cook for an in-depth piece on William Remington, whose Soviet espionage case in the early 1950s was a national news story.

[16] Cook wrote in his autobiography that as a result of his work on the Remington story, he developed "a much more critical and analytical eye" on malfeasance occurring in the highest levels of government and in the judicial system.

He added, "It was quite a change for a noncombative, often conservative fellow who had begun life in a quiet seacoast town on the New Jersey shore and had grown up without any idea that he would wind up writing about the most controversial issues of his day.

Cook would go on to write numerous articles for The Nation—sometimes in collaboration with his World-Telegram colleague Gene Gleason—that took political positions usually identified with the left.

[24] In a 1966 article in The Nation, Cook challenged the findings of the Warren Commission that Lee Harvey Oswald had acted alone in the assassination of President Kennedy.

[26] He wrote an Op-Ed about the 1979 oil crisis for The Washington Post that provoked a critical response from a senior director at the American Petroleum Institute.

[28] Cook's close relationship with The Nation began in 1957 when the magazine's editor Carey McWilliams requested an article on the Alger Hiss perjury case.

The fruit of his inquiry appeared in the September 21, 1957 issue of The Nation in an article entitled "Hiss: New Perspectives on the Strangest Case of Our Time".

[32] Cook wrote in his autobiography that Gleason had been pressured by World-Telegram owner Roy W. Howard to back off the controversial bribery claim.

[33] Cook's 1964 book, Goldwater: Extremist of the Right, initiated a series of events that led to the Supreme Court decision in what is known as the Red Lion case.

After the book appeared, Cook was attacked by conservative evangelist Billy James Hargis on his daily Christian Crusade radio broadcast on WGCB in Red Lion, Pennsylvania.

He also contributed articles for American Heritage magazine: one on the Amistad slave ship rebellion, and another entitled "Allan Mclane Unknown Hero of the Revolution".