All day and night the traffic signal blinks its messages of stop and go.

Berkley professor Dr. Julian Rome is a former code-reader for a government project known as Search for Extraterrestrial Intelligence. His skills are needed to assist Dr. Alexi Gierach in the Antarctic, where strange radio signals are detected. As Julian tries to investigate the hidden messages in the signals of a large unidentified object, he comes into conflict with his fellow scientists Dr. Michael Straub and Dr. Kate Brecher.

Explains how to create various kinds of codes and discusses other means of sending messages, such as Indian sign language, brands, and flag signals.

While promising to open the door to an entirely new type of warfare, a top secret Pentagon experiment suddenly goes wildly out of control. At the same time an observatory in the Sierra Nevada Mountains receives a confirmed extraterrestrial signal. With evidence that the two are connected, a team of commandos rushes the observatory. But, with the goal of immediately sharing the signal, the billionaire who funded the observatory gathers a team of his...