Of #1 New York Times–bestselling author Sue Grafton, NPR’s Maureen Corrigan said, “Makes me wish there were more than 26 letters.” With only two letters left, Grafton’s many devoted readers will share that sentiment.X: The number ten. An unknown quantity. A mistake. A cross. A kiss.X: The shortest entry in Webster’s Unabridged. Derived from Greek and Latin and …