Why Didn't They Ask Evans? (1934)
The two heroes (Bobby and Frankie) of this story are a lot like the Beresford couple. Why Christie didn't continue with this new couple beats me. Frankie is an impetuous young lady with guts and Bobby is a smart young man who loves disguises. This lighthearted and fun story is one of the "can't put this book down" novels of Christie's.
Bobby Jones goes golfing with a buddy. There, Bobby finds a dying man who leaves this world with a cryptic question: "Why didn't they ask Evans?" This starts Bobby and childhood friend Frankie Derwent into fantastic adventures: a chase for an unknown murderer, a near-death poisoning for Bobby, multiple disguises for Bobby and Frankie, a plot to do with mistaken identity, a subplot of a mental hospital and a lunatic patient, a faked death scene, a faked suicide, a scheme of faking a will, a murder in a locked room, our heroes are kidnapped, a scheme with impersonations, and a thriving drug business. Wow! The plot is by far one of the best of Christie's. Absolutely a must read for anyone new to Agatha Christie!