Another romp, fifth in the series, involving Norby the time-twisting robot and his human friends, Jeff, Fargo, and Albany, by sci-fi icon Asimov and his wife Janet. This one has Norby and his friends transported back to the time of the French Revolution by a necklace that is a replica of one belonging to Marie Antionette. The necklace turns out to be failed technology of the Others, supra-beings of the far future; and before all is resolved, our friends have been in the Bastille, in Neanderthal times, and in a false, far-future time line triggered by their excursions. A bewildering plot, with people, robots, and necklaces racing through space and time. Nevertheless, cheerfulness, humor, and excitement abound. As usual, the Asimovs have crowded history, science, and a good yarn into a few short pages.