The footprints from earlier actually lead down the western hall, past two doors and under a door at the end of the hall.

Checking the first door, on the south side of the hall, they see that this room was once a library, with bookshelves around the walls.  Most of the shelves are broken, and in many places they have come away from the wall, tumbling to the floors in moldy heaps.  The few shelves still intact are empty, but a pile of books rests in the southwest corner.

On the north side of the hall, another door opens easily.  This room was once a writing room or study.  Against the wall under the windows sits a large wooden writing desk, partially broken and riddled with damp rot.  There are three drawers in each side of the desk and a large central drawer; the latter is closed, but the others are all open — and two of them have been broken open forcibly.

Following the footprints to the last door, they open it to reveal a wide, mostly unfurnished room.  It may have once been a living room or sun room.  A broken screened door in the north wall leads onto a small patio, the paving cracked and overrun with weeds.  Other than a pile of refuse in the southeast corner, the room is bare.  The footprints travel toward the northwest corner of the room where they come to a complete dead end.   In the floor in that corner, the rough outline of a partially concealed trapdoor, leading down, is revealed.

Tilliman nods his head toward the trapdoor. "Fancy that. Another way down... I'm interested in exploring, but perhaps we should clear the other rooms first. What say you all?"

"Shall we go check the eastern wing, perhaps there is another, another way down" she says grinning.

She would like to check out the books in the library also before we move on, see if anything seem valuable, especially in terms of knowledge.

Investigation: 16

The blue-haired half-elf shares no opinion on where to go next, as before ready to follow along, but following her rescuers she would curiously look through the pile of books for anything interesting and then also take a closer look at the closed central drawer in the desk, first examining it for traps, the trying to open it.

Perception: 11
Investigation: 12

“Tillman I’m gonna put that desk over the trapdoor in the sunroom.  Do you have any idea how to rig it so we’ll hear if someone try’s to come up from there?”  
Eron asks as he attempts to carry the desk over to the trapdoor.  “Those books might fetch a price if they are legible.”

Other then sticking close as Tillman investigates Eron just follows listening.

Before Eron moves the desk, Arlynn investigates the closed drawer.  She doesn't see anything that suggests a trap.  

She can attempt to pick the lock.  [Let's say her thieves tools were stashes in a secret pocket on her armor, so she still has those in her possession.]  She can make Thieves Tools check adding her DEX bonus and Proficiency bonus against DC 10.  She can then make another Investigation check.  

Fane sorts through the remaining books in the library.  The fourteen books in the heap untidily thrown into the corner are covered with cobwebs, vermin droppings, and harmless mold.  All are partially ruined but are still legible.  Most of the books are dull (histories, collections of romantic poems, and so forth), but three are quite noteworthy. These three books bear clear titles on their spines:

• The Magical Properties of Gemstones by the archmage Tenser
• The Magical Properties of Herbs and Flowers by the archmage Tenser
• The Metaphysics of Mathematics by the mage Nystul
• Out of This World Desserts by the planeswalker Ed of the Greenwood

These books are ruined, but their legible contents are still likely of some value to scholars, and a desperate collector might still be interested in possessing half of one of these books.  They are probably worth something, even in their condition.

Inside the third volume lies a piece of parchment torn from a larger sheet, containing a few lines of handwritten text in the Common tongue. Dampness has spoiled it so that only two words are legible: “beyond skeletons.”

[Once Arlynn is done with the desk...]

Eron painstakingly moves the desk a few feet at time, angling it through the narrow doorways and trying to make as little noise as possible.  Eventually he gets it into the sun room and starts to move it into position on top of the trap door.  

When he gets within 5' of the trapdoor, the lights coming through the windows dim as if the sun has been eclipsed, and the sound of a cauldron boiling over fills the room.  A trio of hag's voices boom out from the border ethereal.

"Someone's in our parlor! Someone with a fresh soul!"

“We are the things that were and shall be again!”

"Dead by dawn!"

"Dead by Dawn!  Dead by Dawn!  Dead by Dawn!  Dead by Dawn!  Dead by Dawn!  Dead by Dawn!"  

With that, the voices cease, and the outside lighting slowly returns to normal.

Fane will put the 4 books in her pack, excited to look at them herself, especially the one on Herbs and Flowers.

“beyond skeletons” she mutters to herself, what could that be? She leaves the library and stands in the hall waiting for Arlynn to finish her inspection of the desk. She hears Eron moving a desk in the other room. does she hear the hags?: 9

[To clarify...]

The desk Eron pushes over the trapdoor is the same desk from the study Arlynn is searching.  The voices don't happen until Arlynn is done with the desk and then Eron moves it into the next room.

And everyone hears the voices.  Their cackling, screeching voices carry throughout the halls of the old house.  Fane would likely get a mental 'Hooty hoot hoot?' about the sound from Leo all the way back in the kitchen.

[Got it thanks. Also, it's still daylight right? We have some time before dawn? ]

Fane looks around the room, trying to determine if this is another illusion, either glyph or spell, or something else.

Investigation: 14

She looks over at Tilliman, raising an eyebrow inquisitively.

Tilliman completely ignores the hag business without any reaction at all, easily dismissing it as just another illusion. He considers Eron's question and replies. "Well, I do have some string and a bell I keep on hand for just this sort of thing... However-ehm... That sort of setup really only functions if we remain close-by to hear it. In either case, I think that desk should work pretty well at keeping anyone who's down there from coming up this way..."

As he speaks he keeps his eyes on Arlynn studying the desk for traps. "Erhm... Would you like a hand with that, dear?" He asks with a genial smile on his face, completely ignorant of his guilelessly paternalistic tone.

Fortunately the blue-haired half-elf still has some slender tools hidden on herself that she uses to pick the lock of the central drawer of the desk.
Thieves tools: 25

"Does it look like I need help Professor?" Arlynn says with a confident smile as she swiftly picks the lock. "You might assist me with examining this though." She adds casually as she takes a closer look inside.

Investigation: 16

Eron looks white as a sheet the idea of an enemy materializing near him out of thin air has startled him once the desk is bumped into place he draws his swords again, then heads towards the east wing once everyone is done investigating.  “Tillman I’m not a fan of these magic alarms I believe someone or a group of someones knows we are here.  When you were taken captive how many did you see Arlynn?  Oh and Fane Leo has not noticed anyone moving about that end of the manor has he?”  Did any dusty prints track into the eastern hallway main floor?

"Only saw four of the pirates but they mentioned others, so a fair number I would venture to guess, nothing we can't handle though right? They won't catch me twice I can tell you." The blue-haired half-elf says confidently, giving the blade-wielding human an encouraging smile.

Eron is starting to think pirates a haunted house a lookout from an upstairs window…

”I’m beginning to think this is a smuggler’s base.  I wonder if there is a path down to the water.  They watch for their ship, have a base below and spread rumors of a haunted house.  Very clever.  What do you all think?  If you seen four let’s assume there’s at least a couple more six maybe.  If we find a way down to the shore there’s probably a cove or something that they are guarding where they move their loot.  I’ve got a feeling they know we are here.  What do you guys want to do?  Continue exploring till we get jumped, look for a way down maybe surprise them, or head back and report?  I’m with you whatever we decide.”

Earlier, Arlynn unlocked the deck drawer almost effortlessly.  While unlocking it proved no challenge, getting the swollen wood unstuck and sliding out the drawer was a bit more of a process.  Eventually, the drawer relented and she was able to slide it out.  The drawer contains nothing but old, valueless documents, all written in Common — receipts for purchases of various chemicals and laboratory equipment.  

Popping the drawer open revealed a hidden compartment above the drawer, which opens and drops down.  Inside, an old leather bag contains two potions.  One of them is quite recognizable as a common potion of healing, while the other is less easily identifiable.  It is thick liquid the color of brick, with a green dot inside.

Eron, meanwhile, doesn't find any tracks leading into the other hallway.

After Eron makes his suggestion, the party hears a door slam somewhere at the rear of the house.

At the same time, Fane gets a message from Leo:

Fane will share with the group what Leo just told her. “Someone entered the kitchen from the scullery, which has stairs to the basement and retreated. They may know we are here, but perhaps did not know about the centipedes? With the trap door covered, we could wait in the middle room for a few minutes and see if someone emerges from the rooms we haven’t checked yet. Perhaps they don’t know we are here and will try another way up? Thoughts?”

Additionally, she’ll say to Eron, "I think your deductions and guesses are valid as far as this being a hideout for the pirates and possible smuggling, but I vote for continuing clearing the house and getting to the bottom of things here before we leave and report. Plus, I think our new blue haired friend wants her stuff back!”

She will then move here and wait.

"I can confirm the white-haired elf is quite right about the blue-haired friend..." Arlynn says with a quick grin. "...her stuff would mean a lot to her. Also, my mission at least is investigation this house, but once I've done that and we still haven't found those pirates or smugglers or whatever they are then I would be happy to tag along down to the beach." She continues with a pleasant smile. "I think we should keep moving though, cautiously of course, starting with following that someone. Maybe they have a secret hideout under the house, maybe it is even connected to the sea, that would make sense right?" The blue-haired half-elf suggests as she follows along for whatever her rescuers decide.

Perception to notice threats: 21

Eron follows along as Fane and Arlynn move out to the foyer.  “Tillman, what do you say?  Find Arlynn’s gear, and see what transpires?”  Eron checks the first room to the right of Fane.

Tilliman's eyes continue to greedily explore every single crevice of every single room he's in. He answers Eron's question distantly, "Yes yes yes. I enthusiastically concur... Who knows what else we might find in such a pursuit."