BBY/ABY is used to position items along the Star Wars Timeline. BBY refers to Before the Battle of Yavin. ABY refers to After the Battle of Yavin. The Battle of Yavin in Episode IV: A New Hope occured in 0 BBY/ABY.
Obi-Wan Kenobi has left the Jedi Order in order to help end the Civil War on Melida/Daan. But the Young leaders, and Obi-Wan himself, will soon discover that winning a war and ruling a planet are two separate tasks. He will be tested as he forges ahead with his new path without his master to guide him.
While Obi-Wan helps shape the new government on Melida/Daan, Qui-Gon comes to grips with his second failed Master/Padawan relationship back at the Jedi Temple on Coruscant. Things at the temple are not at rest, nor is Qui-Gon’s soul.
Books 5-7 form a unified story arc.