[2] In Washington, D.C., police captain Frank Matthews's career is on the rise, having just been appointed consultant for a powerful U.S. senator.

One evening, after appearing at a political function in Baltimore, Matthews decides not to return home until the following morning.

The next day, he is informed by authorities that his wife has been discovered shot to death while in bed with her lover, who was also killed.

Pendulum also features a side-plot involving a death row inmate, Paul Sanderson, convicted of rape and murder, who is set free due to a legal technicality.

Ironically, now that Captain Matthews is a suspected murderer, he hires Sanderson's lawyer, Woodrow Wilson King, to represent him.