Thinktwice was an orbital penitentiary in which Majenta Pryce was once incarcerated. The Tenth Doctor ran into her for the second time while she was a prisoner at the facility, and they together shut down the facility — which was conducting various illegal experiments on its inmates using the Knowsall machine. In truth, the jail's staff were being manipulated by the Memeovax.

Amongst its staff were William Flatch, Royce and Jonah Gripton.

Its residents included Majenta Pryce (known therein as "Empee"), her cellmate Zephyr (also known as ZY 6/18/5/5, or "Zed") and Ceecee. (COMIC: Thinktwice)