Plett was a male Ho'Din Jedi Master for the Old Republic. He established a Jedi Enclave on the planet Belsavis.
During the Clone Wars, he had established a relationship between himself and the Jedi apprentice, Nathaniel Kenobi. When the Jedi Purge occurred, he closed Belsavis' system to space travel, but allowed renegade Jedi to enter.
Eventually, Nathan gave Plett and the Jedi coordinates to the new clone/Kaminoan colony of Novus Kamino Prime. He served as one of three Jedi Masters, whose responsibilities were to follow the instructions of Nathan.