Robot Mountain — Stephen Goldin

By sheer accident, the Imperial Special Investigation Service has stumbled across a fiendish plot against the Empire--using a time bomb to blow up the tsaritsa and throw the galaxy into chaos. Now, to learn the truth, its agents must infiltrate a hollow mountain, the lair of a mad robotic genius... while simultaneously, another team is protecting Her Majesty from a hidden assassin. And somewhere, a time bomb is ticking....