Murder Planet was the name devised by Jankom Pog and ultimately chosen for the sole class M planet found in the Hirogen star system. While choosing the name, Rok-Tahk offered the alternate suggestion of "Larry" and Dal R'El voted for the name "Let's not visit M class planets again." When Zero attempted to telepathically ask the planet its name, they discovered that the planet wished only to eat them. (PRO: "Terror Firma")
A Klingon Bird-of-Prey once landed on the planet and never left; Gwyn was of the opinion that the crew did not survive the planet. There were rations left behind, as well as one warrior's mek'leth. (PRO: "Terror Firma") The planet was later explored by the crew of the USS Protostar in 2383, where it was discovered that despite its abundance of flora, the soil contained no nutrients. (PRO: "Dream Catcher")
On further investigation, it was determined that the planet was in fact a sentient lifeform– a superorganism that lured and consumed its prey for nutrients, by way of emitting spores that clouded the minds and senses of its visitors. The planet then sensed and fabricated its victim's dreams or nightmares onto its vine-like cilium, to entice them to stay, and once fully enthralled, would begin to wrap them in its cilium and gradually pull the unaware being into the ground. If the prey became aware of these tactics and resisted, the same tactic would also be used to pull or hold down landed starships, or destroy small craft and vehicles by crushing and pulling them beneath the surface, stranding their intended victims. (PRO: "Dream Catcher", "Terror Firma")
To further disorient its prey, as well as their tricorders, the planet was able to terraform its surface at will by suddenly moving hills. This tactic could be defeated by using a fixed point, such as the stars, for navigation.
During their first contact mission to the next planet they visited, the Cymari homeworld, Rok described the threatening cymatic phenomena they experienced as "it's Murder Planet all over again." (PRO: "First Con-tact")