Book excerpt: By day, she's Mrs. Mallowan, hospital pharmacist. By night, she's Agatha Christie, queen of crime. Doing her part for the war effort, Agatha dispenses medicine in shell- shocked London. But the world's most renowned mystery writer is troubled. Compared to the horrors of World War II, her detective novels seem trivial and quaint. When a Jack the Ripper-style murderer strikes, Agatha lobbies her friend, forensics expert Sir Bernard Spilsbury, to take her to the crime scenes. But the killings are far more gruesome than any that her fictional detectives have ever solved. Can a crime writer also be a crime fighter? Joining forces with London's top investigators, Agatha risks her life to stop the monstrous serial killer. With this ripped-from-the-headlines mystery, author Max Allan Collins presents a blood-stained valentine to the most celebrated author of detective fiction.