Death's Deal

Death's Deal was named "the deadliest planet in the galaxy."

History
The planet boasted a variety of highly deadly animal and plant life, including highly toxic coral fields, massive tunneling rock worms, and sentient plants that could paralyse victims with their scents. There were also a high volume of crashed spaceships on the planet surface, all of which continued to send out automated distress beacons long after the crew had been killed on the planet; only planetary surveyor Merrit Erskine was known to survive on the planet for any length of time. Deadliest of all, however, were the large supply of slaughter crystals beneath the surface of the planet. Because of these reasons, it was forbidden to attempt to land on the planet, although thrill-seekers were willing to pay small fortunes to say that they had walked on Death's Deal, even briefly.

Responding to the many distress beacons, the Tenth Doctor and Donna Noble, accompanied by Krux and Merrit's daughter Lyric Erskine, became involved in a mission orchestrated by the Eleventh Doctor to stop the Wraith Mining Corporation from mining the planet for the slaughter crystal deposits. In the process, the Doctor learned that the native life of the planet was susceptible to the electronic signatures of higher technology, being driven into a frenzy by the numerous distress beacons in downed spaceships all over the planet.

The Doctor was eventually able to send a signal to detonate the automated mining probes and shut down the distress beacons, calming the wildlife (although he admitted you still would not want to get near most of the life forms on the planet). He encouraged Krux and Lyric to continue Merrit's original research on the planet before he and Donna departed. (AUDIO: Death's Deal)