Thirteen Diamonds by Alan Cook
Series: Lillian Morgan, Book 1.
Approx. 56,520 words.
Published on April 10, 2010.
Lillian Morgan is bored with life in a retirement community, but she gets more excitement than she hoped for when a fellow resident drops dead at the bridge table—while holding a perfect hand of thirteen diamonds. Intrigued by the astronomical odds against this happening, she uses her mathematical background plus assistance from her granddaughter and friends to prove that a murder was committed.