Alex immediately felt scared by the old story of a ghostly pirate.

“It’s just a stupid scary folk tale,” he told himself as he hurried up the hill.

The road doubled back and forth across the face of the hill, rising higher all the time. Brineblood scarecrows were skewered on wooden posts outside every house. Alex tried to keep his eyes away from the scrawled faces and crooked limbs. Light from the old rock lighthouse stationed at the mouth of the bay flashed across the water intermittently, casting fleetingly eerie shadows throughout the town.

Halfway up the hill, Alex spotted a white light bobbing fitfully towards him. He shielded his eyes to recognize Mrs Bilge shuffling along the pavement, a head torch strapped over her white hair. Behind her waddled her old dog Cannonball, surely named for his round, sagging belly that swept the ground as he walked.

The old lady swivelled her head to aim the light at the plastic box tucked under Alex’s arm. “What have you got there?”

“I’m just, um…taking my octopus for a walk.” Alex had never been brilliant at coming up with excuses. Kraken waved an arm in greeting.

Mrs Bilge adjusted her glasses, squinted at Kraken balled inside the tub, and gave an approving nod. “It’s important to get them exercise. I have to keep my Cannonball here in tip-top shape!”

The old dog wheezed and rolled onto his side like a beached seal. Mrs Bilge tugged sharply at the lead, dragging Cannonball away in her wake.

At the top of the hill, the winding road straightened onto a long driveway lined with overgrown trees and black iron lamp posts, their light long since faded. Alex had to feel his way cautiously through the darkness to reach the tall gate of the old aquarium, rusted and hanging open.

HAVEN BAY AQUARIUM read a sign above the gate. HOME TO THE WONDERS OF THE DEEP SEA!

The aquarium had been built over a hundred years ago; an imposing house of iron and glass set against the sky. The curved roof rose into a grand domed top. It must have sparkled like a jewel once. Now the panes of glass that forged its walls and roof were cracked and spattered with bird droppings. A CLOSED sign hung crookedly on the entrance doors. Underneath it in red paint somebody had scrawled FOR EVER.

Kraken grew more agitated now they had reached the aquarium. She climbed up to perch on the rim of the plastic box. The tug of the green glow was so much stronger here. Alex pushed the glass doors but a heavy padlock held them closed.

“We’re not getting in this way.”

Nearby, part of the glass wall had long ago cracked and fallen away, leaving a gap just wide enough for him to carefully squeeze inside.

The old display tanks stood like portals to drowned worlds where strange and fearsome creatures once reigned. The wide entrance hall narrowed like a funnel into the boulevard of glass tanks that formed the central path of the aquarium – Oceanic Avenue. Most of the tanks still brimmed with murky water, brown gunk drifting like autumn leaves falling in slow motion. Enough light from the nearly full moon shone through the glass ceiling high above to pick out sunken ornaments – diving bells, shipwrecks, stone sea serpents – bearded with thick skins of algae.

The glow intensified as Alex let it pull him along the faded mosaic path between the tanks and along the length of the aquarium. The inhabitants were long gone, but Alex couldn’t shake the feeling that he was being watched, as if the ghosts from his dreams were real.

To one side, a crudely painted sign invited visitors to enter BRINEBLOOD’S GHOST SHIP. Inside, a sharp-toothed animatronic dragon used to burst from the waves and gobble up a dummy dressed as a pirate. Now the entrance was shuttered and sealed.

Kraken tugged on the edge of the box to urge them onwards. At its furthest end, Oceanic Avenue led to a soaring archway fitted with tall, baroque double doors. As he approached, one side creaked haltingly open. Green light spilled out. A series of rapid click-click-clicks skittered ahead of him, punctuated by short, sharp squeaks. Alex felt his legs lock with fear. Still, the light seemed to beckon him. He took a breath of stale air and forced himself to step through the archway.

The back of the park had housed the main attraction: the dolphin tank. A hexagonal wall of glass long and sheer, twice his height. Although Alex knew now that the tank had always been a cruel prison for animals as energetic and free as dolphins, their lithe and limber antics had never failed to delight him as a child.

A dense jacket of algae and impenetrably cloudy water disguised the source of the green glow inside the tank. Still, it cast enough light to pick out four scampering shapes on the path. Alex yelped in surprise.

Four sea otters froze and peered up at him warily. Each carried a fish in their jaws. Clearly his arrival had interrupted their work, though what exactly that was remained unclear.

“Um, sorry?” he said.

The otters tilted their heads in consideration. Button noses sniffed, sprays of whiskers waggling. Kraken clambered onto Alex’s shoulder and shifted her colour to mirror the soft green shining from the tank.

Apparently this was signal enough for the otters to resume their business. One by one they dropped their catch at the base of the tank. The largest of them then huddled low so that another could clamber onto its back. The third repeated the trick before the smallest otter carefully ascended the teetering stack to perch at the top.

Next, the fish were passed up mouth-to-mouth, deftly tossed and caught, for the otter at the pinnacle to sling over the top of the tank and into the water.

A realization shuddered through Alex. “They’re feeding something.”

Kraken climbed up onto his head and yanked painfully at his hair, like a cowboy taming a wild horse. Alex dutifully inched closer to the glowing water.

A sudden whisper almost knocked him over with fright. He glanced around in panic but there was nobody else there. Yet a voice nagged at him, spoken in waves breaking and seabed shifting. The same voice the ocean used to taunt him. It was coming from inside the tank. Alex prepared to run. Except…the voice was filled with sadness. Defeat. Whatever it belonged to was trapped there. And it was asking him for… Every time Alex almost caught the word it was washed out of his reach.

Taking a breath to steady himself, Alex lifted a hand and pressed it against the cool glass of the tank. The glow inside intensified, responding to his touch. It cut through the floating filth like a lighthouse beam, breaking apart the algae on the inside of the tank. The glass grew clear in a perfect imprint of his hand.

Every beat of Alex’s heart felt like a depth charge detonating. Whatever was inside the tank was asking him to look. He lowered his eyes to the cleared portal. The water was still grubby, but the green radiance revealed a little of what lay inside.

A coiled, grey shape, lying still. A sunken log, perhaps, or a piece of broken machinery left to rust.

Until it moved.

An eye opened on the other side of the glass. Its milky pupil caught him in its ravenous gaze.

Alex cried out and staggered away from the tank, bowling over the tower of otters. The animals chattered indignantly as they scattered apart.

“Hey!”

The shout echoed from the other side of the archway, bouncing around the glass walls. Alex whirled around to see torchlight wavering closer.

The green glow inside the dolphin tank vanished like a snuffed candle, plunging him into darkness. The otters rushed away past his ankles. A tug at his hair from Kraken shocked Alex to his senses. He turned to run just as the beam of a torch picked him out.

“Who’s there?” demanded its owner.

The archway was blocked. Alex was trapped. There was no choice but to surrender.

Still perched on top of his head, Kraken reared up tall like a spitting cat and let fly a jet of water towards the torchlight. A startled cry was followed by the light clattering to the ground.

Now Alex didn’t waste any time. He barrelled through the archway, ran back along the promenade of barren tanks, and escaped through the gap in the wall.