The titular justice is a cranky member of SCOTUS, Howard Wynn, who seems to be losing it. Before he loses his faculties, he loses consciousness, leaving his clerk, Avery Keene in charge of his well-being, and saving America from its president. (Where does she get this stuff?) There is a sophisticated mystery to solve, some of it based on chess and some on clues left by Wynn for Avery, and occasionally Wynn's son, Jared (why did she choose that name??? and why is the sympathetic FBI agent named Robert Lee???) to unravel. The plot is compelling, and I appreciated sharp descriptions like

"Ruthlessly pampered"
"serrated by jealousy" and
"she had made ingratiation her blood sport"