Factions of Phandalin - Iniarv's Tower
This book goes over the various rules around the faction of the Harpers in Phandalin and the Forgotten Realms, making it easy for any new or veteran DMs to integrate it more into the core stories being told, and making the faction feel more useful for the players that choose to join.
The adventure sees the characters on a mission to Iniarv's Tower, sent to search for the artifact, Bowgentle's Spellbook, and rescue the fellow Harper member, Brodven.