Anyone who has followed the journalism and books of New York Times columnist James B. Stewart over the past few decades is familiar with his skills as an accomplished storyteller and the insight and detail he brings to his reporting of financial scandals, corporate goings-on, and political and legal affairs. In Deep State: Trump, the FBI, and the Rule of Law (Penguin Press, $30), he examines the handling of both the 2016 probe of Hillary Clinton’s emails and the investigation of links between Russia and the Trump campaign. Donald Trump, of course, has repeatedly denigrated the Russia investigation as some sort of sinister conspiracy by the “deep state,” a nebulous network of career bureaucrats, intelligence agents, military officers, and law enforcement officials bent on protecting their own power. Is there anything legitimate about this claim? Or are Trump’s incessant attacks on the investigators simply acts of obstruction meant to cloak his own illegal conduct? Those are among the central questions that Stewart gets at in his lucid and timely book.