Locke (Idris IV) is the sole inhabited planet in the Idris system, United Empire of Earth (UEE). Terraformed and colonized by Humans in the early 26th century SEY, it was captured by the Tevarin in 2542 during the First Tevarin War and used as a main strike hub for the Tevarin fleet while it was under their control. It became the site of the Battle of Idris IV in 2544, a key engagement that turned the tide of the war in favor of the United Planets of Earth (UPE) and launched Ivar Messer's political career. Much of the landscape that was destroyed via orbital bombardment has since been rebuilt, though some craters remain.
A thriving tourism industry is based in the city of Tanys, located in the Corsti Mountains. Additionally, the planet is famous for the quality of its brandy and cognac.