Anyone of a certain age can remember when assassination was a tragic fact of American political life. In the 1960s came the slayings of John F. Kennedy, Malcolm X, Martin Luther King Jr. and Robert F. Kennedy; in the 1970s and ’80s, the near-fatal shootings of George Wallace and Ronald Reagan. And yet, since Reagan’s close brush with a deranged gunman in 1981, no American president has been caught in the cross hairs of an assassin. One might think that this owes something to the competence and professionalism of the Secret Service, the agency we depend on to protect our leaders. Think again. “Zero Fail,” a history of the agency by the Washington Post reporter Carol Leonnig, is a devastating catalog of jaw-dropping incompetence, ham-fisted mismanagement and frat-boy bacchanalia. The Secret Service’s tradition of drunken debauchery goes back to at least November 1963, in Dallas, when some agents apparently got so hammered in a gin joint just hours before the fateful motorcade that they could barely walk, much less leap to the president’s defense. More recently, on a trip to Cartagena, Colombia, to prepare for Barack Obama’s visit in 2012, 11 members of his Secret Service advance team were shipped home after a night of boozing and cavorting with prostitutes.And drunken escapades are the least of the agency’s problems. Created in 1865 to chase counterfeiters, the Secret Service did not formally start protecting presidents until 1901, after William McKinley was gunned down in Buffalo. Today it guards current and former presidents, vice presidents and their families; major presidential candidates; visiting heads of state; diplomatic missions; and “major events” like the Super Bowl. Yet the agency, like some generals, has been fighting the last war. There were improvements in techniques after John Kennedy’s assassination. But since then the Secret Service has been stretched thin by its expanding charter; hobbled by inadequate training and obsolescent weaponry; and plagued by mistrust between the rank-and-file and leadership.The agency has also been abused by its overseers — the institutional equivalent of a battered child. Congress has starved it of necessary funding. And some presidents have thumbed their noses at their protectors. Kennedy defied his detail to keep up with his round-the-clock extramarital adventures. Bill Clinton also went rogue, ditching his agents to go over the White House wall without warning. Donald Trump treated his protectors like a Praetorian Guard — politicizing their leadership and making outlandish demands: While recovering from Covid-19, he bundled agents into a limousine for a theatrical victory lap around Walter Reed National Military Medical Center, thereby inviting their infection.Time and again, in Leonnig’s telling, rather than taking a bullet for the president, the Secret Service has dodged one. No place on earth is supposed to be more secure than “Crown,” as the White House is code-named. And yet, in September 2014, a 42-year-old man wearing Crocs and carrying a knife clambered over the fence, lumbered across the North Lawn and into the East Room before he was tackled by an officer. Three years later, another “jumper” strolled unchallenged up to the eastern entrance. A multimillion-dollar system of sensors, canine patrols and human agents had gone kaput.I found myself wishing that “Zero Fail” included more examples of Secret Service successes: threats discovered and plots disrupted. Still, Leonnig writes, “it is for the Secret Service’s front line and its future that I write these hard truths … because they deserve better.” True enough. This book is a wake-up call, and a valuable study of a critically important agency. The Secret Service needs adequate resources, competent leadership and respect. It is, after all, the thin line between the president and disaster.