A picture-book account of how Allen Pinkerton formed the first U.S. detective agency in the mid–19 th century culminates in his prevention of an assassination plot against Abraham Lincoln shortly after he was elected president. After brief biographical information about Pinkerton, the author describes the development of the Pinkerton Method, things considered standard for private eyes today, such as undercover work. The second half of the book deals with Pinkerton’s investigation of an 1860 plot by secessionists to assassinate Lincoln in Baltimore. How Pinkerton and his staff, which included several female detectives, first uncovered and then foiled the plot with the complete cooperation of President Lincoln reads like a good mystery, with twists and turns. The faux woodcut illustrations printed in shades of orange and purple give the book a jaunty and appealing look. (Ages 8–11)