" 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 commonly found in science, medicine, and religion. The most graphically dramatic letter.

Notoriously tricky to pronounce: think xylophone. X: The twenty-fourth letter in the English alphabet. Sue Grafton's X: Perhaps her darkest and most chilling novel, it features a remorseless serial killer who leaves no trace of his crimes.

Once again breaking the rules and establishing new paths, Grafton wastes little time identifying this sociopath.