Doctor Who: Time Reaver (The Tenth Doctor Adventures, #1.2)

Calibris. The spaceport planet where anything goes. Where anyone who doesn't want to be found can be lost, and where everything has its price. Where betentacled gangster Gully holds sway at the smugglers’ tavern, Vagabond’s Reach.

The alien Vacintians are trying to impose some order on the chaos. Soon the Doctor and Donna discover why. An illegal weapon is loose on the streets. A weapon that destroys lives… Slowly and agonisingly.

The Time Reaver.