This thread follows a group of scientists in the United Kingdom connected with the University of Cambridge and their attempts to warn the past of the impending disaster by sending tachyon-induced messages to the astronomical position the Earth occupied in 1962–1963.

He and his student assistant, Albert Cooper (also likely based on the author and his experiences at UCSD), discover that the noise is coming in bursts timed to form Morse code.

The resulting message is made of staccato sentence fragments and jumbled letters, due to the 1998 team's efforts to avoid a grandfather paradox.

Since the message also gives astronomical coordinates, he also shares it with Saul Shriffer, a fictional scientist who is said to have worked with Frank Drake on Project Ozma.

Ramsey believes it to be an intercepted military dispatch hinting at Soviet bioterrorism, while Shriffer thinks the message is of extraterrestrial origin.

In 1998, Ian Peterson recovers a safe deposit box in La Jolla containing a piece of paper indicating that the messages were received.

There he interrupts Lee Harvey Oswald's assassination attempt on President John F. Kennedy, attacking the shooter and sending the would-be fatal third shot awry.

The concluding chapters portray the 1998 of the original timeline as a bleak, failing world, the intensified ecological disaster taking a noticeable toll on the human way of life.

The scientists whose work stemmed from the signal are honored, including Bernstein, who receives the Enrico Fermi Prize for his discovery of the tachyon.