On October 20th, 1980, Ronald Reagan wrote the president of the air traffic controllers' union a letter calling their working conditions "deplorable" and promising his administration would fix them. PATCO endorsed him three days later. It was the first time the union had ever backed a Republican.

Ten months into his presidency, 11,400 controllers walked off the job. Reagan gave them forty-eight hours to come back. When the deadline passed, he fired every single one of them, broke the union, and dared the FAA to keep the planes flying with less than a third of its workforce.

The planes kept flying. The consequences took longer to arrive.

This week we hit Control Z on the forty-eight-hour deadline, and follow what happens when the president who promised to fix the system decides not to destroy it.

On a computer, Control Z is the undo button. When you press it, whatever you just typed gets reversed and allows you to make a different decision.

What if you could press control Z on some of the biggest decisions in history?

In October of 2016, Bob Iger was 48 hours from buying Twitter for $15 billion. Both boards had approved. The lawyers were drafting. Goldman Sachs was working the weekend. Then Iger went through the user data one more time, read his own notifications, and couldn't sleep. Sunday morning he typed an email to his board with the subject line "cold feet," called Jack Dorsey, and killed the deal. Twenty-eight days later, Donald Trump won the presidency.

Fourteen months after that, Disney bought 21st Century Fox instead, and Disney+ followed.

This week we hit Control Z on the Sunday morning phone call, and follow what happens when the man who runs Disney decides to own the platform that hosts the president.

In November of 1095, a sixty-year-old French pope stood in a field outside the cathedral of Clermont and gave the most consequential speech of the Middle Ages. Eight months earlier, ambassadors from the Byzantine emperor had asked him for a few thousand professional knights to help fight the Seljuk Turks. Standard contract work. Urban II sat with the request through the summer, then walked outside on November 27th and offered something nobody had ever heard before. Full remission of sins for everyone who took the cross. The crowd shouted back, "Deus vult." God wills it.

They asked for soldiers. He gave them a holy war.

This week we hit Control Z on the speech that launched the Crusades, and follow what happens when one man writes the smaller answer.

In September of 2000, three guys from a tiny DVD-rental startup called Netflix flew to Dallas on a chartered jet they couldn't afford to make a pitch to the most powerful video rental chain on Earth. Reed Hastings asked Blockbuster CEO John Antioco for fifty million dollars. Antioco's mouth twitched at the corner. His general counsel told the room the dot-com hysteria was overblown. The Netflix guys flew home crestfallen. Today Netflix is worth four hundred billion dollars, and the only Blockbuster left in America is a tourist attraction in Bend, Oregon.

He almost said yes.

This week we hit Control Z on the deal that would have killed Netflix in the crib, and follow what happens when one man writes the check.

In April of 1979, the Chicago Bulls had a coin flip against the Los Angeles Lakers for the first pick in the NBA Draft. The Bulls' marketing department had run a fan vote on what to call. Heads won. Bulls GM Rod Thorn, who'd called tails his entire life, looked down at the marketing handout and said heads. The coin came up tails. The Lakers got Magic Johnson. The NBA you know was built on what came next.

He almost called tails.

This week we hit Control Z on the coin flip that built the modern NBA, and follow what happens when one man trusts his gut. Showtime, the Bulls dynasty, Phil Jackson, all of it changes.

In December of 1936, King Edward VIII signed a piece of paper that changed a thousand years of British monarchy. He gave up the throne to marry Wallis Simpson, an American divorcée his government refused to accept as queen. His brother Bertie became George VI. Bertie's daughter became Queen Elizabeth II. The House of Windsor you know exists because of what Edward signed that day.

He almost didn't sign.

This week we hit Control Z on one of the closest-run constitutional crises in British history, and follow what happens when a king who wants something more than the crown decides to keep both. The ripples reach further than you'd think.

In December 1989, NBC had a pilot nobody wanted. "The Seinfeld Chronicles" had tested as one of the worst pilots in network history, the president of entertainment called it "too New York, too Jewish," and Fox had already passed. The show was dead. Then a specials executive named Rick Ludwin canceled a Bob Hope special on his own budget and used the money to order four more episodes, the smallest sitcom order in American television history.

But what if he doesn't? What if Ludwin lets the pilot die the way everyone at NBC expected? What happens to Larry David? What happens to the next 35 years of American comedy? And does the last great shared audience in American television history ever exist at all?