Prerequisites: Max out Helene's level 1 friendship
Reward: None
Unlocks: Helene level 2 friendship, An Unknown Artefact
As far as villagers go, Helene can be somewhat tricky to locate. Though she's in charge of the Arcade Centre in the basement of the Lazy Bowl Tavern, Helene doesn't seem to spend an awful lot of time at her post. More likely you'll find her wandering the south of Moonbury Town, reading on a park bench or talking to someone in her spare time. Still, if you want a somewhat reliable place to find her, you should always check the Arcade Centre.
Once you've boosted Helene's friendship level a notice will go up on the Bulletin Boards of Moonbury Town. This one is from Osman, and he's trying to ensure that Dean keep the doors of Town Hall locked. He mentions something about the Police Department, so make a point to head there between 13:00 and 20:00, Tuesday to Sunday.
Approach the Police Department and you'll see Derrek and Dean out front, and Helene is keeping a close eye on them. She'll briefly hit on Dean, then... leave. Something sketchy is afoot. Visit the Arcade Centre between 18:00 and 23:00 and you'll receive a tarot reading from Helene, as well as resolve the quest. (Though her explanation isn't terribly convincing.) Moving to the second level of friendship with Helene will allow you to proceed towards the next quest in her story, An Unknown Artefact.