Fresh fish, never frozen

The inside of the stagecoach was lavish, far too posh for the usual sensibilities of the retired Tabaxi. They shifted somewhat nervously back and forth, occasionally popping a knuckle or scratching at something. Across the seat, Stray's patron lounged, a snifter of dark blackberry brandy in one hand.

"I'm sure you have heard the requests of many others for your services," he began, and sipped at the deep purple liquid. "It means a great deal to me that you have accepted mine. You have such a reputation--"

"Please, please let's not fall into small talk. I've been out of that practice for as long as I've been retired. If you must talk, then tell me everything about this problem. When it started, what you have seen and heard, whether you've been to see it up close yourself. Everything."

The nobleman looked momentarily perturbed. It was plain that he wasn't used to being interrupted, but given the circumstances surrounding his hiring of the renowned stranger he could not do much about it. He cleared his throat, took another sip, and then shut his eyes.

"Yes, of course. Well. It's been there for what I can assume is a week. At any rate it hasn't been there longer than the last full moon, I hosted a party in the very clearing where it currently... sits? Stands? What do portals even do? But anyway, it hasn't been long. I have not been closer than fifteen or twenty feet from it, as I value my own life and do not have the sort of reckless and headstrong bravery that those of your profession often display."

Stray wrinkled their nose slightly.

Continuing, the man gestured with the glass. "As far as I know, nothing has come out of it, but I haven't been sitting in front of it at all hours of the day. It seems to emit a low-frequency humming sound, and it hovers about a foot from the grass. I can walk all the way around it and it seems to have no physical depth, and it seems to look the same from both sides."

In Stray's mind, they reconstructed the scene from the given facts. There were plenty of possibilities, of course. Planar gates were uncommon at best, but they did sometimes show up in strange places thanks to the absent-minded mistakes of powerful wizards. There was also the possibility of a tesseract-like linking of two places on the same plane, but that generally didn't just appear from nowhere. That required a concerted effort from two or more parties at the beginning and end locations. They flicked through a mental catalogue of other magical possibilities for a moment, but lacking any more information, it was impossible to narrow it down much further.

The two of them rode in relative silence until the coach clattered to a stop on the hard cobblestone that led to the ferryman's dock. The patron pushed open the coach door and slipped out, seeming glad to be away from the awkward atmosphere inside, and hailed the ferryman. 

"Master Chemsay," Stray heard the ferryman call back. "I reckon you've found who you were looking for, then?"

"I have, and I will thank you to mind the business that is yours while I mind mine. Put off your boat and ferry my coach across to the island," Master Chemsay said. "If you don't mind, I've many things to do before the day is up, and the longer I stay here, the fewer get done."

The horse and coach clambered onto the wide deck of the ferry, and as Stray poked their head out of the window to look around, they caught sight of a few gathered folk at the dock who had, evidently, been waiting for the ferry's departure but who were all ushered off the vessel so that this "Master Chemsay" could jump the line and hire the whole ferry for their own private voyage. Stray caught the eye of one of the waiting folk, and made an apologetic face-- well, as apologetic as a cat could look. They returned a dirty, sidelong glance. Retreating back into the coach, they began collating all the information they had about this Chemsay fellow, and a tiny, almost imperceptible sliver of regret at having taken the money of a man who appeared to be a real piece of work began to grow in the back of their mind. And yet, with the kind of money that Stray had requested and received approval, the cat could do much more than just buy a few parcels of trading cards. Perhaps some actual good work might come from the Chemsay gold.

Chemsay elected to sit on the front of the coach during the trip, occupying the space the driver normally sat. Likely this was to continue to avoid having to sit silently in a cramped room with a moody cat, but it suited Stray well enough. From their place inside, they could see the water lapping at the edge of the ferry, the ferryman and the driver idly chatting, and what must be the Chemsay estate's island approaching. Perhaps it was a trick of the light, but curiously, Stray thought they could see a strange, unnatural sheen to the surface of the water the closer they approached to the island.

"...but the rumours of weird things in the water recently? Them rumours are rightly true," the ferryman's voice carried to the coach. The driver glanced nervously at the water as the ferryman continued. "Been about six months or so since I started seeing things down in the dark. Come out at night, they do, and often I'll find little dead fish or that ilk washed up on the edge of the ferry, bites taken out or torn up or worse."

"But it's not dangerous, is it? To be out on the water like this?" the driver's tremulous question came.

"Course not, not when it's broad daylight like this. Especially when it's me at the helm, on account of everything what lives in water knowing that I'm the boss in these parts." The swish of the rudder paddle and the splash of the small ripples breaking on the ferry seemed to agree with him. He knew what he was doing, that was at least certain. "Can't do much about the dead things what show up in the water, though. Rather likely that the merfolk don't much care for this inky oil, either."

Stray stretched, and slipped out of the coach, sitting down by the edge of the ferry to look at the water. Sure enough, there were streaks of a sickly green oily substance on the surface of the water here and there-- that was the strange colour they'd seen. They leaned over, and dipped a claw into the oil.

As if it were a bear trap and Stray had stepped in it unseen, a sudden splash was followed by a bony blue hand that shot out of the water in the blink of an eye, grabbing Stray's wrist and heaving downward toward the surface of the water. Never one to be caught by surprise, though, Stray's reflexes kicked in instantly, and their claws dug into the wooden surface, anchoring them in place. With a flourish of the open hand and a single eldritch word, a swirling miasma of red and blue mist appeared and dissipated, leaving in its place the long, straight wooden staff that Stray knew so well. Their fingers closed around its haft, and just as quickly, they thrust the end of it into the water, striking something rubbery under the surface. The hand grasping their wrist loosened, and they wrenched free from the grip.

"On your guard!" they shouted. "Something in the water, and it's not friendly." Their keen eyes scanned the surface again, looking for any disturbances, but the oily deposits made it difficult to see past the ripples.

The ferryman pulled up the rudder paddle and wrenched a cutlass from its sheath. "No kidding? It's broad daylight, what are they at?" he stuttered. "What did you see?"

"Blue skin, fingers like a man, grip like a serpent, smell like a dead seagull," Stray called back. 

"That sounds like merfolk, but what--"

The ferry lurched, pushed from below by something strong. Chemsay shouted and scrambled to the center of the ferry, as far from the water's edge as his claret velvet coat could get. There, at the lower corner, a pair of hands, clawing wildly at the wood and pulling its body onto the boat. Stray leveled the staff at it, and muttered another word, watching the energy collect in the staff and aiming toward the thing. It managed to pull itself onto the deck, a body covered in long, matted black hair tangled with aquatic vegetation, emaciated slick blue skin pulled tightly over an erratic skeleton whose bones jutted at awkward angles. Its fingers were long, with entirely too many joints that curled and uncurled.

"Mermute," the ferryman said. "Don't let it bite you, it carries plague!"

Stray let the gathered magical energy release, firing two bolts of eldritch magic at the creature. One of them struck true, the other fizzling into the surface of the oily water. The Mermute's form staggered with the impact, but it struggled to its malformed feet, a hunched figure draped in draggled hair and detritus, two shining white eyes visible under its slick wet mane.

"Kill it!" shouted the coward Chemsay. "Destroy it, for the love of the gods! Keep it away from me!"

Stray slid their feet forward and readied themselves, already beginning to gather more magic, but for as besotten as this creature was, it was surprisingly fast, closing the distance between them in an instant. Claws swiped wildly at Stray's face, beaten away only barely as they spun the staff around their body. They planted their back foot and pivoted, driving the staff into the creature's ill-defined form and levering toward the water. As the thing slid from the impact, it lashed out with a claw, scraping across the back of Stray's leg.

Stray's staff flashed bright blue, and a gout of multicoloured flame erupted from the wound, engulfing the Mermute. The oil that dripped from it caught fire, and with a terrible scream it scrambled off the edge of the vessel and back into the water, a sizzling, bubbling sound following its disappearance. Stray's ears strained to hear if there were more, or if it had come back up, but all seemed silent.

There was a moment of tense quiet, before the ferryman spoke up. "Seen plenty of Mermutes in my day, but that one was something else. Looked like it'd been mashed up and stretched back out or something."

Stray knelt down and looked at the wound on their leg. Nothing too deep, but it should still be cleaned and tended to. As they unbuckled their pack to find bandages and alcohol, they glanced back at Chemsay.

"You know anything about that thing?" they called.

"N-no, I've never seen anything like it before," Chemsay answered. "Nothing at all."

Stray made a new mental note about the nobleman:

When he lied, he rubbed the palm of his left hand with his right thumb.