Askalon V

Askalon V was a Class M planet located in the Alpha Quadrant. Although there was evidence that a civilization once thrived on the planet, by the late 23rd century the planet was barren and uninhabited, and only the ruins of that long-lost civilization remained.

In 2294, the USS Enterprise-B received a distress call from the surface of Askalon V and altered course to investigate. Upon arrival in orbit, Captain John Harriman led a landing party to the surface to try and locate the people that needed rescuing. However, the party found nothing but ruins, but something had affected Ensign Demora Sulu, and she began attacking members of the landing party. Harriman was forced to fire multiple phaser shots at Sulu in order to stop her attack, and unfortunately she was dead before she managed to get medical treatment aboard the Enterprise. (TOS novel: The Captain's Daughter).