London in 1910 is the setting of “One Fatal Flaw”, Anne Perry’s third chronicle of the conscientious young lawyer Daniel Pitt, whom a woman begs to defend her boyfriend from a charge of murder. He accepts the case and wins it, with the help of expert testimony from a highly regarded forensic pathologist. Then the same woman demands Pitt (and his expert witness) save her from conviction of an identical crime. Pitt is certain his unwelcome client is guilty. “We’ve got to be seen to try our damnedest to get her off, yet see to it that we fail,” he says after devising a daring double-game to serve both justice and his own conscience.