Once home to seven and a half billion souls, the Melkner system is now dead, bar a few plants and lesser creatures in the depths of the seas of Unity.

Barely two hundred years ago, the worlds Unity and Constance thrived with monks, devoted followers of the Imperial Creed and monuments to the God-Emperor and his saints. The shrine worlds were an established stop on the Carthaxian pilgrimage routes, and devotees travelled the length of the sector to walk amongst the marble statues of Constance and bathe in the healing seas of Unity.

In 800.M41, reports of a disturbance in the warp around the system reached sector command. They were soon followed by garbled distress calls that spoke of an 'Outsider' in the system, and 'ghosts' walking among the people. When the next pilgrim vessel arrived, its hails went unanswered. Investigators found the population dead in the streets, as if war had broken out and all had been compelled to fight to the death. Inquisitor Epsis of the Ordo Obsoletus found deep space pict captures of a planet never before recorded in the system. Thorough searching of deep space found no such planet, and Epsis theorised that the system had been visited by a rogue planet. Research showed that catastrophe often followed the arrival of rogue planets; Epsis quoted four previous cases in the sector in the previous three millennia in his presentation to the Carthaxian Conclave. The complete loss of life he attributed to mass mania.