Golden Idol Investigations: The Lemurian Phoenix Review (Katosepe)
This has been my favorite of the DLC packs and possibly my favorite Golden Idol story to date. This story is almost entirely standalone so it's easy to jump right in no matter how long you've been away from the franchise. Going from 4 to 5 cases allowed Color Gray to not necessarily give another tutorial but it offers a case that isn't quite as brutally difficult as some of the other DLC cases have been, letting you get back into the mindset without needing to remember the lore of the base game at all.
While relatively simple by comparison to the base games, The Lemurian Phoenix offers up a tight story and some fun cases to solve, leaving you feeling accomplished and satisfied with the experience. If you only play one DLC pack for Golden Idol, it should be this one (but I'd recommend not limiting yourself like that!)