The Leap Second

A North Korean spy. A US technology firm. A shady spy agency. The Chinese government. An aging mathematician who escaped the Nazis.
What links them all?
When advanced encryption software is needed for sensitive communications, strapping the system to a commercial satellite might be the only option for the US government. But this leaves them potentially exposed and there are operatives who would exploit any weakness for their own gains.
And when a weakness is exposed, disaster threatens as quick as a second.