Arisys, make an arcana check.

You all leave the tavern. You walk across the square and a couple buildings to your left to reach what appears to be the general store. When you enter, you look past shelves of supplies to see Kerowyn sitting at a counter against the back wall. She is a well-dressed human woman of about fifty years old with fair skin and long, dark blonde hair streaked with silver. She glances up and smiles upon seeing you, but her eyes are sad.

"I heard there were travelers in town. I was wondering if you'd stop by." Her accent is ever so slightly off - she's not from around here.

Summer takes a bow. "Yes, we actually wanted to speak with you. My name is Lady Summer Halo of Critwall, and these are my companions." she swept her hand to her companions, allowing them the opportunity to introduce themselves. "We'd like to talk about the reward you posted in regards to your children?" The tone in Summer's voice was somber but friendly.

(Persuasion: 15)

Kerowyn bows her head respectfully. "It's a pleasure to meet you, Lady Summer. I am Lady Kerowyn Hucrele of Greyhawk." She pauses for a moment to take in the group of adventurers that has entered her store. "One year ago, my two children entered that ravine, and they have yet to return. I offer you 250 gold pieces each if you can recover their bodies, or at the very least, their signet rings. If by some miracle they have survived and both are returned in good health of mind and body, I will double the reward." Her voice is calm and regulated, but her eyes are desperate.

Genken bows, "Lady Hucrele, your grace and beauty precede you. I have heard much of you in the courts of Greyhawk, though have never had the pleasure of meeting. I am Genken Medjhan," he says as he places a hand on his chest, "I would be more than happy to assist you with this search. Might you describe your children and their rings to ease our identifying them as the time arises?"

Oh sorry....Arcana: 14 

(Apologies for the late replies over the past couple days, work has been hectic.)

Arisys, you haven't heard of anything like this before.

Kerowyn smiles. "I was always told that Sharwyn looked just like me. Same hair, same eyes. She was studying magic, and getting quite good at it, before..." She chokes up momentarily, but regains her composure. "Talgen took after his father. Taller, darker hair, more muscular. He always carried a large wooden staff around, one that would make you think he was a magic user, too, but no, he just liked hitting things with it. Their rings will look just like mine." She places her hand on the counter in front of you so you can see the large gold ring nestled on her finger. It's engraved with an intricate family crest and her name.

Arisys tries her hand at a curtsie like she has seen nobles do before, "Arisys Albaratie. I am very sorry for what you are going through. We are headed into the Twilight Grove anyway, so it is no trouble to keep an eye out for your children. It must be hard to have lost two so young."

"Real sorry about your kids, ma'am." Ondrej chimes in awkwardly. "If they're still alive we'll bring them back."

"Thank you. Thank you all. If the gods will it, this will bring me some closure, one way or the other." Kerowyn gestures to the room. "Please, have a look around. If you need anything for your journey, I will give you a discounted price."

Summer looks to see what items are available.

You are able to find any basic adventuring gear, which you can purchase for half of the PHB cost. There are no weapons, armor, or ammunition for sale. If asked, Kerowyn will tell you that you'll need to visit the blacksmith to acquire these items.

Anyone who wants can make an investigation check.

Genken Investigation: 22

Edit: purchase some chalk for 1cp as well.

Investigation: 6 

Arisys is interested in anything that looks interesting, but will also purchase a crowbar (halved is 1gp) and a grappling hook (halved is 1gp).

EDIT: I guess I'll also need some rope (Hempen halved is 5sp)

Genken and Arisys, as you search for the supplies you want to purchase, you notice an odd-looking box wedged in the back of a shelf. Its ornate carving seems out of place among the store's other wares, and it's covered in dust, as if it's been sitting there for months.

"Is the box for sale?" Arisys points to the ornate box on the shelf. "Can I see what is inside?"

"What box?" Kerowyn walks around the counter towards where you're standing. Her face softens when she sees it. "That's one of Sharwyn's old things. I didn't even know it was in here. You're welcome to take a look if you'd like; I had no idea what she kept in there."

"I would be most interested." Arisys will take the box from Kerowyn and set it on the counter in front of them. 

(Can she take 10 minutes to ritual cast Detect Magic?)

Kerowyn watches with curious eyes as you cast Detect Magic on the box. You notice an aura of both Abjuration and Evocation magic coming not from the box itself, but from something inside it.

As Summer eyes Arisys performing her ritual, she sees a dungeoneer's pack that piques her interest. 

"What did you find with the box? Is it locked, Arisys?" Genken says, twirling a lock pick around his fingers. Seeing Arisys pick up a grappling hook, Genken nods, Good idea, he thinks. (He'll pick up one of those as well for 1gp).