Secarus IV was the fourth planet in the Secarus system.
In 2345, the Albino retreated to a fortified compound on this planet after he escaped from Kang, Kor, Koloth, and Curzon Dax on Galdonterre.
In mid-2370, Kang learned of the Albino's location and traveled to Secarus IV. When Kang arrived, the Albino immediately contacted him, offering Kang a proposal. The Albino offered Kang, as well as Koloth and Kor, one last glorious battle against forty of his finest sentries.
Three months later, the three Klingon warriors, along with Jadzia Dax, returned to Secarus IV to finally face the treacherous Albino. After successfully destroying the compound's armory and power station, the Albino was confronted and killed, fulfilling the Klingons' blood oath and their eighty-year quest. (DS9: "Blood Oath")