The Four Horsemen are reunited. Cassandra is their prisoner. And worst of all, Methos has apparently rejoined his old comrades. As MacLeod makes plans to rescue Cassandra and face Kronos for the last time, Methos tries to learn why his companions have gotten back together after thousands of years while attempting to make his peace with Cassandra -- who was his "pet" during her first captivity in the Bronze Age. Kronos' plan is revealed: he intends to use an engineered virus to wipe out most of humanity and conquer the survivors as part of an eternal empire. Methos eventually betrays his former comrades, with he and MacLeod simultaneously battling Kronos and Silas to the death in their own respective fights. The result is a double quickening as MacLeod and Methos win the day. Cassandra wants to avenge herself upon the redeemed and remorseful Methos, her former tormentor, but Duncan exhorts her to let him live. The centuries have truly changed Methos after all, and he had in the end helped to save humanity. Afterward, Methos implies that he had set up the entire confrontation with Kronos hoping MacLeod could do what he himself never could -- take his Immortal brother's head.
Tracy Scoggins Cassandra
Here's the text of Revelation 6:8 from the Revised Standard Version of the Bible:
"And I saw, and behold, a pale horse, and its rider's name was Death, and Hades followed him; and they were given power over a fourth of the earth, to kill with sword and with famine and with pestilence and by wild beasts of the earth."
This episode was, in fact, the 100th produced episode of the series.