A Vulcan world with a monastery that hid a secret listening post spying on the Andorians, exposed by Archer and destroyed in 2152.
P'Jem is a planet with an ancient Vulcan monastery, a sacred site visited by pilgrims. It is the home of a community of Vulcan monks and holds important religious artefacts. However, beneath the monastery the Vulcan High Command operated a secret long-range sensor array used to watch the Andorians, despite claims it was only a religious retreat.
In 2151 Andorian soldiers took the monastery and its visitors, including Captain Jonathan Archer, hostage while hunting for proof of the spying station. Archer discovered the array and gave the Andorians evidence of it, a move that angered the Vulcans but won him Andorian respect. In 2152 the Andorians destroyed the monastery after warning the monks to leave, and the Vulcans blamed Archer and moved to recall T'Pol from Enterprise, though she ultimately remained aboard.
P'Jem shows how much the Vulcan High Command was hiding behind its strict and peaceful image. It began the long and complex relationship between Archer and the Andorian commander Shran, and set the stage for later reforms in Vulcan society.