Coruscant Nights by Michael Reaves
A memorable trilogy of character-driven adventures in the seedy underworld of the city planet Coruscant. Inspired by the film noir detective movies of the 1940s and 1950s, these books tell the story of a self-doubting Jedi survivor, a sarcastic droid, and a plucky ex-journalist who come together with other interesting characters to solve mysteries and join the budding resistance in the early days of the Empire.
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Book 1: Jedi Twilight
Book 3: Patterns of Force
Story continued in The Last Jedi.
This is a classic era book from the Legends timeline. It will likely be contradicted by newer books, movies, or TV shows (if so, just think of it as an alternate universe).