Aprilia III

Aprilia III was the third planet in the Aprilia star system, in the Alpha or Beta Quadrant of the Milky Way Galaxy.

Environment
The planet had a unique radiation belt that prevented the functioning of transporters and apparently interfered with subspace communications.

The planet had green vegetation and animals, including a lizard-like creature with six legs and bird-like creature. 

History
An unidentified alien civilization constructed relay station on Aprilia III some centuries before the 23rd century. It was later abandoned and left untouched, but was still powered.

In the late 2260s, a team of Federation archaeologists, led by project manager Professor Jefferson Whitmore and including Doctor Paula Zarlenga, visited Aprilia III. They spent several months studying the technology of the relay station but found it incomprehensible and inoperable. At some point, Cybermen infiltrated the facility and mind-controlled the researchers, making them unemotional and docile.

After the archaeologists missed making three scheduled reports, the USS Enterprise (NCC-1701) was sent to investigate on stardate 3368.5 and Captain James T. Kirk, Mister Spock, Doctor Leonard McCoy and Lieutenant Commander Montgomery Scott traveled to the planet's surface in the shuttlecraft Galileo (NCC-1701/7) (II). They met with Professor Whitmore, who blamed the lack of communications on the radiation belt and gave them a short tour of the station.

But suspicious of the archaeologist's behavior, they returned at night to covertly investigate, only to be interrupted by, who'd also visited the planet in his TARDIS. He helped them break the lock and together they infiltrated the facility. There, they discovered the archaeologists under the control of the Cybermen and attempted to free them. A battle ensued and the Cybermen were destroyed with the Doctor's aid, while the researchers were liberated. The technology activated itself shortly afterwards.

Kirk later arranged for a garrison of Starfleet Security personnel to protect the archaeologists against further Cyberman incursions.