In the dead of night, a seal flopped out of the ocean and onto the beach. It wriggled a bit under the cover of darkness, and a moment later a beautiful woman was folding a large coat over her arms and walking along the sand. Between them, the coat and a flowing mane of hair covered her body, which was handy because she wasn't wearing any clothes.

The beautiful woman walked until she reached somebody's discarded picnic: plastic wrappers, bottles, drinks cans, a half-eaten ice cream cone and other such items. Upon seeing this, the woman threw down her coat and crouched down for a closer look. She spent some time on this, not noticing a flurry of activity in the darkness behind her.

'Oh, aye,' the woman said, in a thick Scottish accent. 'This will do for a start.'

She stood up, turned round and tried to pick up her coat. She found that it was gone, and a look of dismay came into her face.

'You know,' a male voice said, 'New York's beaches really aren't as dirty as you might think.'

The woman turned her head in the direction of the voice, and narrowed her eyes on the face of its owner.

'What,' she said, in dangerous tones, 'have you done wi' it?'

The sun had risen when Roland, Garrett, Kylie and Eduardo found themselves once again shooting through the streets of Manhattan in the Ecto-1.

'So,' said Garrett, 'what kind of ghost would have something against an overpriced fashion outlet?'

'Maybe it's a communist,' said Eduardo.

'Or an animal rights activist,' said Kylie. 'That place sells coats made out of rodents and cosmetics made out of whales.'

'They don't use whale products in cosmetics anymore,' said Roland.

'Maybe the ghost doesn't know that,' Kylie said smartly.

'Some cosmetics use whale vomit,' said Eduardo.

'What?' said Kylie, turning in her seat to frown at him.

'It's true,' said Eduardo. 'But it's okay because collecting whale vomit doesn't harm any animals.'

'The whales are probably glad to get rid of it,' said Garrett.

'So,' said Eduardo, 'the products are labelled as cruelty free. Your makeup could have whale spew in it, Kylie.'

'I don't believe that for a moment,' said Kylie, turning to face the front again, and looking worried for just a split second as she did so.

'All right,' said Roland, as he stopped the car. 'Enough talking about whale vomit. We're here.'

The foursome got out of the car, strapped on their equipment and headed for the store entrance. The PKE meters were already buzzing. Roland, who was leading, opened the door to the sight of a young woman and an older man exiting the building. Both were carrying large shopping bags, and the woman was wearing a man's smart jacket over bare legs and high-heeled shoes. The man barged Roland out of the way before he had a chance to step aside; the woman tottered along behind on her high heels without a glance at any of the Ghostbusters.

'Rude,' said Garrett, glaring down the street after them.

'Never mind,' said Roland. 'Come on.' He led the way inside the building.

'I cannae walk in these things!' the woman called after the man, in her Scottish accent, for she was the very same one who had appeared on the beach the night before.

'You'll learn,' said the man. 'I know all about how you people work. You have to do what I tell you.'

'Ah dinnae!'

The man stopped walking and turned to face her. 'What?'

She stopped as well, let out a sigh of exasperation and said, 'I do not.'

So saying, she put down her bags and lifted first one foot and then the other to remove the shoes. She then picked up her bags and walked on down the street barefoot.

The man bent down to retrieve the discarded shoes. Then, hurrying to catch up with the woman, he said, 'I'd like my jacket back now.'

'Huh!' said the woman. 'You're nae the only one! I will find it, Andrew.'

'What's your name, anyway?' Andrew asked.

'I havenae one.'

'Then I'll call you Lucille.'

She rolled her eyes. 'Och, saints preserve us!'

'My jacket, Lucille,' Andrew said firmly.

Lucille stopped walking, put down her bags again and took off the jacket. Underneath she was wearing a short, sleeveless dress.

'You could put on some pants and a sweater if you want,' said Andrew. 'You don't need to look fancy for this friend of mine.'

'I like the cold,' said Lucille. 'Who is this friend, anyway? You dinnae want me for yourself?'

'Wait and see,' said Andrew. 'I guess I'd better call him first. He'll never believe it, of course. Unless... you can prove it, can't you? You have some kind of power or something. Those were the Ghostbusters back there. They were there for you, weren't they? Lucille, what did you do?'

'I do as I please, Andrew,' said Lucille. 'You're nae my master.'

'Well,' said Andrew, 'just be careful. You don't want those Ghostbusters onto you.'

Lucille laughed. 'That sorry-looking lot we passed back there? They cannae do anything to me!'

'Oh yes they can, so you'd better behave. Come on.' Andrew put his hand on Lucille's back and propelled her down the street.

The Ghostbusters were in the part of the store that happened to be filled with women's underwear. Roland was standing as far as he could get from the items of stock, looking awkward. Eduardo and Garrett were keeping straight faces as they took PKE readings. A saleswoman was standing anxiously by, and Kylie was feeling an item of lingerie between her thumb and first two fingers. She looked at her PKE meter, then at the price tag on the underwear, which made her eyes widen.

'Unbelievable,' she muttered to herself. Then she turned to face the room at large, and said, 'This stuff is all absolutely soaked.'

'I know!' said the saleswoman. 'It'll be ruined! Some of this lingerie is –'

'You know, miss,' Roland said quickly, 'there's a good chance all this damage will be undone if we catch the entity.'

'When we catch the entity,' said Garrett, turning his chair to face the woman and putting away his PKE meter. 'So what else can you tell us?' He glanced at the name tag on her jacket. 'Phillippa.'

'Oh dear, I don't know!' said Phillippa. 'A lot of people were shopping in here... no ghosts or demons that I could see... and then just after I left, there was the most terrific splash and everyone came running out all wet! Now they're all demanding that we pay for their dry-cleaning bills and give them store credit!'

'Well,' said Garrett, 'as my colleague has explained, that may not be necessary.'

'You say this was just after you left?' said Kylie. 'You're a personal shopper, right, Phillippa? Who were you personal shopping with? Anybody in particular?'

'Yes,' said Phillippa. 'It was one of our regulars, Andrew Hunter. He was here shopping for another trophy girlfriend. Oh, that was so unprofessional... I'm sorry...'

'We won't tell anyone,' said Roland. 'Go on.'

'Well,' said Phillippa, sounding increasingly agitated as she talked, 'he comes here from time to time with a beautiful woman to dress. He picks out her underwear and everything. Well, obviously.' She gestured around her. 'And he gets me to help, even though he makes all the decisions. I do try to make him buy things the woman likes...'

'Hey,' said Eduardo, 'you gotta make a living. He's the jerk, Phillippa, not you.'

'So this happened after you left with them,' said Kylie. 'Well, that may or may not mean something.'

'It could, you know,' said Phillippa. 'There's also been some damage done in cosmetics and women's wear and women's shoes. That's all the places I took them.'

'The same kind of damage?' asked Roland.

'Yes,' said Phillippa, 'and up in cosmetics, there's a huge kind of pudding in the middle of the floor from the creams and stuff, with the containers thrown everywhere.'

'Has anyone else noticed this place stinks of fish?' asked Eduardo.

'It sure does,' said Garrett. 'And salt. This is seawater.'

Kylie gave the underwear another good rub with fingers and thumb, then licked her forefinger.

'It's salt water all right,' she said. 'And, uh... hopefully it's not poisonous or anything.'

'Is it important whether it's seawater or not?' asked Phillippa.

'It may help us to determine what we're dealing with,' said Kylie.

'Could we maybe take a look at another department now?' Roland asked awkwardly.

'Absolutely,' said Phillippa. 'I'll take you to women's shoes.'

She led them down three steps and out into a rotunda full of desks and helpful signs pointing to various doors and staircases. They walked through areas labelled Returns, Customer Enquiries and finally Management, where a harassed-looking man was shouting down a telephone receiver, 'I need four of the strongest dehumidifiers in existence, up here, now!'

'I really hope we can clear all this up for you, Phillippa,' said Roland.

'Right,' said Eduardo, not loudly enough for Phillippa to hear. 'Otherwise they might only make six figures this quarter.'

'All right,' Kylie said, as they walked into a damp room full of overturned shoe racks. 'I think we get the picture. We'd better check that the readings all match, and ask around to see if anyone else saw anything. If we can't find the entity on the premises, I think we should talk to this Andrew Hunter character. He's the only lead we have right now. Phillippa, can you give us his address?'

'Yes,' said Phillippa, 'if you don't tell my boss it was me.'

'Phillippa,' said Garrett, 'I wouldn't tell a soul.'

'My lips are sealed,' said Roland.

'No hablo inglés,' said Eduardo.

'All right,' said Phillippa. 'I'll find it while you're finishing up here.'

Back in the Ecto-1, the four Ghostbusters updated Egon on their progress over the radio.

'Saturated with seawater?' Egon said. 'Fascinating. And you say no one on the premises in any way sensed the presence of a supernatural being. The things you describe could have been done by an ordinary person, of course, but not without detection.'

'We may have a link with this Andrew Hunter person and his trophy girlfriend,' said Kylie. 'Egon, is it possible she could be some kind of mermaid?'

'Anything is possible,' said Egon.

'Why would a mermaid trash a department store?' Eduardo asked sceptically.

'Because she was there with a male chauvinist pig,' said Kylie. 'I might have trashed the place too, if I was there with him.'

'But you wouldn't be there with him,' said Eduardo. 'So why would a mermaid? She didn't make a deal with the Sea Witch so she could go places she didn't like with a guy she didn't like.'

'Maybe she didn't know she didn't like him,' said Garrett. 'Maybe she got to "Daddy I love him" before she bothered getting to know the guy.'

'Let's try to avoid using classic cinema as our primary point of reference, shall we?' Egon's voice suggested.

'Of course,' said Roland. 'Eduardo makes a valid point though, Egon. If this woman's a mermaid, how is she walking on land, and why is she going to places she doesn't seem to like?'

'I'll look into that,' said Egon.

'Bearing in mind that we don't know this woman has anything to do with anything,' said Kylie. 'I do think it's worth going to see her, though. And him. They were in all the places that got trashed, so they at least might have seen something.'

'All right,' said Egon. 'Keep me informed.'

It turned out that Andrew Hunter lived in an exclusive apartment block with huge balconies and uncommonly clean windows.

'This is a nice place,' said Garrett, who was struggling to move his chair through ankle-deep rubbish in the forecourt. 'Think how much nicer it would be if someone collected the trash occasionally.'

'Stinks of fish again,' said Eduardo.

'I'm getting traces,' said Roland, who had got out his PKE meter.

'The first thing we have to do is get past this doorman,' Kylie said, approaching said doorman and giving him a winning smile. 'Good morning.'

'You're the Ghostbusters!' said the doorman. 'Did somebody call you about the trash?'

'Well,' said Kylie, 'we –'

'You wanna know what I saw? Well, I'll tell you. It all came down the stairs and the garbage chutes on these giant waves! You kids smell that damp?'

'Sure,' said Eduardo. 'So we better get up there and investigate, hadn't we?'

'Yes, yes, of course,' the doorman said, and he stepped aside to let them in.

They went to the elevator, and Roland pushed the button to call it. The doors opened at once, and all four Ghostbusters let out a yell as they were saturated with water. The impact sent Garrett's chair careening across the lobby, and knocked the other three off their feet.

'What the...?' said the doorman, turning to stare at them, then looking down as the water reached his ankles and soaked his trouser bottoms. 'Where is all this water coming from?'

'The ghost again, sir,' said Roland. 'We'll get right on it. You know,' he went on, turning back to his teammates, 'I doubt that elevator is completely safe.'

'Aw man!' Eduardo said, as he helped Kylie to her feet. 'The dude lives in the penthouse!'

'Well, I'm taking that elevator,' said Garrett.

'No!' said Roland. 'I'm telling you, it's not safe!'

'You don't want to be trapped in an elevator, Garrett,' Kylie said significantly.

'I could live with that,' said Garrett, not meeting her eye. 'But I guess it would be inconvenient, so if you guys really insist...'

'We do,' said Roland, already at the staircase with his hand on the banister. 'Don't worry, Garrett – we won't miss out a single detail.'

Roland knocked on the door of the penthouse apartment. Andrew Hunter opened it a crack, and his one visible eye widened in alarm.

'What are you doing here?' he demanded.

'Good morning, Mr Hunter,' said Roland. 'We're the Ghostbusters, and we're investigating –'

'I don't know anything. Go away.'

'Sounds suspicious,' said Eduardo, looking at Kylie, and she nodded solemnly.

'Suspicious? Me? Don't be silly!' Andrew said, and he flung the door wide open. 'This is about the department store, isn't it? I heard the commotion, but I didn't see anything.'

'What about the woman who was with you?' asked Kylie.

'She didn't see anything either,' said Andrew.

'Well,' said Kylie, with an edge to her voice, 'maybe she can tell us herself whether she did or not.'

'Girl's got her own mind, man,' Eduardo added.

'By the way,' Kylie said, holding up her buzzing PKE meter, 'whatever was in the store is now here, or has been very recently. We'd better check you and your friend for demonic possession.'

'Uh... that's okay,' said Andrew. 'Look, I really don't think I can –'

'Andrew!' came Lucille's voice, from somewhere inside the apartment. 'How do I make the water run cold?'

Andrew turned in the doorway as Lucille entered the living room, clutching a towel to her body. Eduardo's jaw dropped. Roland looked interested just for a moment, then acutely embarrassed.

'Get back in there, Lucille,' said Andrew. 'I'm busy.'

'Actually, miss,' said Kylie, now staring at her PKE meter, 'we'd really like to talk to you, if you have a minute.'

'Oh, aye,' Lucille said amicably, and approached the doorway. The PKE meters went mad. 'What's all this, now?'

'Lucille!' hissed Andrew.

'Perhaps you'd like to put some clothes on first,' said Roland, unable to look at her.

'Och, nae need,' Lucille said cheerfully. 'I'd wear my own coat if I could, only somebody's hidden it,' and she took a moment to glare at Andrew before smiling again at the Ghostbusters. 'What are you wanting to ask me, then?'

'What do you know about the strange activity in the department store this morning?' asked Kylie.

'Why should I know anything?' asked Lucille.

'Because this device here,' said Kylie, indicating her PKE meter, 'is telling me that either you're a ghost or demon of some kind, or you've been in very close contact with one, very recently.'

'Is it now?' asked Lucille, looking at the PKE meter with interest.

'That's enough,' said Andrew, grabbing Lucille's arm and pulling her behind him. 'Go and take that shower. Turn the twisty thing all the way to blue if you want it cold, all right?'

'I'll find it, Andrew,' Lucille said, as she turned and made her way back into the apartment.

'No, wait!' said Kylie. 'Stop her, you guys!'

'Um,' said Eduardo, still staring.

'What are you going to do?' said Andrew. 'Shoot her? Look at her – she's not a ghost!'

'Lucille!' Roland called.

Lucille turned, and looked coquettishly over her shoulder at him. 'Aye?'

'Would you rather come with us?' Roland asked. 'You don't have to stay here.'

'Och, but you're a sweet lad,' said Lucille, smiling. 'I'm all right, now, don't you worry. What's your name, by the way?'

'Roland,' said Roland.

'I'll remember that,' said Lucille, as she began to slink off. 'Fare thee well, Roland.'

'What the heck was that?' Andrew demanded, once Lucille had left the room.

'I'm not sure she's safe here,' said Roland, looking Andrew squarely in the eye.

'From me,' Andrew bristled, 'or this demon of yours?'

'Both!'

'You don't know what you're talking about,' Andrew said, and slammed the door in their faces.

There was a moment of silence. Then Eduardo said, 'Now what?'

'Back with us, are you?' said Kylie.

'She's no monster,' said Roland. 'He is!'

'I know what you mean, Roland,' said Kylie, 'but she could still be responsible for all this. I was getting a much stronger reading off her than him. He may be the monster, but she's the demon, if it's either one of them. And if not, I don't know what to make of these readings.'

'So what do we do?' Eduardo persisted. 'The dude was right – we can't go in there and start blasting her. That's private property, and she might not even be a demon.'

'But she doesn't know how to work a shower,' said Roland.

Eduardo shrugged, and said, 'Maybe the controls are different wherever she comes from.'

'Surely she'd know that red means hot and blue means cold,' said Roland. 'Anyway, why would she want to take a cold shower?'

'Well...' Eduardo began.

'Come on, you guys,' said Kylie, 'there's nothing more we can do here for now. Let's go.'

Back at the firehouse, Roland and Garrett had joined Egon at his computer. The monitor was flicking through various pictures of men and women, some covered with flippers and gills and a blue or green hue, some looking perfectly human, and everything in between.

'Accounts of merfolk sightings are extremely varied,' said Egon, 'and goodness knows how much they've been coloured by the various afflictions one might face on a long sea voyage. Some legends say that merfolk can conjure storms at sea, and they have powers of divination. The idea that one would come onto the land and damage human dwellings is completely unprecedented, although there have been a few reports of merfolk promising vengeance for the pollution of the seas.'

'Well,' said Garrett, 'this woman puts seawater and trash everywhere. That's got to be a mermaid!'

'It seems likely,' said Egon. 'My research hasn't turned up any better explanation. And you say she looks just like a regular woman, legs and all. Fascinating.'

'Is that right, Roland?' Garrett asked. 'A regular woman from top to toe? I'm sorry I missed that.'

'She was decent, Garrett,' Roland said severely. 'Well, more or less.'

'Are you sure you can't be more specific about the accent?' asked Egon.

'Sorry,' said Roland. 'I'm not very good with accents. Irish, Scottish, something like that? But listen, Egon, I can't believe she's evil. I think she needs help.'

'Oh, come on, Roland,' said Garrett. 'Just because she looks nice in a towel...'

'Garrett,' said Roland, 'you know me better than that. This Andrew Hunter guy is a jerk! Lucille's probably just trashing everything because she doesn't want to be with him.'

'Then why is she?' asked Garrett.

'I don't know!' said Roland, in tones of enormous frustration.

'It could be that he has her under some kind of enchantment,' said Egon. 'Come to think of it, I believe I have read something about men enslaving beautiful women from the sea, but as far as I recall it's all completely unsubstantiated.'

'What's this about beautiful women?' Janine asked, entering the vicinity with Slimer bobbing along in the air behind her. 'Should I be jealous?'

'Never, Janine,' said Egon. 'We were just discussing mermaids. Roland, Eduardo and Kylie believe they found one in a man's penthouse apartment this morning, but they say they can't be sure. Perhaps I'd better go and take a look at her. Um, I mean...'

'I know what you mean,' said Janine, smiling slightly.

'Can I go with you, Egon?' asked Roland.

'She's cast some kind of spell on you, dude,' said Garrett.

'She has not!' said Roland.

Slimer sniggered, and sang in his high-pitched babble, 'Roland's in lo-ove!'

'Stop it, children,' said Janine. 'Egon, before you go, I have the department store manager on hold. He wants to speak to you. Apparently someone promised that all the dry-clean only underwear would magically go back to normal, and he wants to know what's taking so long.'

'I didn't promise,' Roland said apologetically to Egon.

'Give me a minute to deal with this, Roland,' said Egon, getting to his feet. 'Then we'll go and see about this mermaid of yours.'

Kylie was sitting on the couch with a heavy tome in her lap when Eduardo came in from the kitchen with an empty soda can, which he tossed into the bin. He then went to stand behind Kylie, looked down at what she was reading and said, 'I like her.'

'Sure you do,' said Kylie, with a dry smile. 'It's easy enough to have a perfect body when you're a drawing.' She turned the page. 'See? He's nice too.'

'Yeah?' Eduardo looked at the illustration of a well-built man standing ankle-deep in water next to a boat. 'You'd be okay with him docking in your harbour, huh?'

'Well,' said Kylie, 'maybe not. He's a selkie.' She turned back to the previous page. 'So is she.'

'A selkie,' Eduardo said. 'Okay, got it. Y en inglés, por favor?'

'Merpeople who can walk on land,' said Kylie. 'It's all here – try reading it for yourself. Or are you still on chapter books?'

Eduardo stooped over, leaned his elbows on the back of the couch and read, 'When in their skins, at sea or on land, selkies are indistinguishable from common seals.'

'Very good,' said Kylie.

'So these things can take off their seal skins, and then they just look like regular people?'

'Yep.'

Eduardo carried on skimming on the page. 'Then guys come and steal their skins and hide them, so the selkies can't return to the sea and they have to marry the guys. Well... they don't have to.'

'Maybe they can't think of anything better to do.'

'I can,' said Eduardo. 'How about, find her skin and get the heck outta there? What about your chico on the next page? Does anyone steal his seal skin?'

'Not according to this book,' said Kylie. 'It says he can bring human women under his spell, but there's nothing about stealing his skin or marrying him. In fact, it says he particularly likes women who are already married and aren't happy with their husbands.'

'So male and female selkies have the same effect on people, but no matter which one is the selkie and which one is human, it's always the man who has the power. That don't sound right.'

'This book isn't necessarily right about everything. The legend reflects the time in which it was written, and that must have been centuries ago.'

'Okay,' said Eduardo, 'I get it. These seal people could easily be real, but it's probably not true that the guys are all jerks and the girls are all doormats. Maybe they both just come onto the land to get some exercise, and some people find them... you know...'

'...alluring,' said Kylie.

'Yeah.'

'How's it going?' Roland asked loudly, appearing at the top of the stairs.

'Um,' Eduardo said, rising quickly to his full height and taking a step back from the couch. 'It's going great, man. I mean, this selkie stuff seems to fit. Right, Kylie?'

'I don't know,' said Kylie. 'It says here that selkies are a peaceful race, and it doesn't say anything about them having magical powers, like the more traditional brand of mermaid.'

'Can I see that?' Roland said, sitting down beside Kylie and holding his hands out for the book. She gave it to him.

'But all these mermaid legends have the same roots, don't they?' said Eduardo. 'Why shouldn't these selkie things have the same powers as the others? And why shouldn't some of them be evil? We were just talking about bias – maybe they're not victims at all.'

'But Lucille is a victim!' said Roland, running his eyes over the page. 'You met that Hunter guy. Maybe she's just doing all this because she's angry and frustrated.'

'Well,' said Kylie, 'you may be right. We can't rule out everything else, though.'

'What everything else?' asked Eduardo.

'Like maybe she's the regular kind of mermaid,' said Kylie, 'and they actually can walk on land. Or maybe she's not a mermaid at all.'

'But it all fits!' Roland insisted. 'Look, you've read this stuff about men stealing the seal skins and forcing the selkies to marry them. Remember, Lucille told Hunter she'd find something? And... oh my gosh, you guys – she even said he'd hidden her coat!'

Eduardo and Kylie exchanged a look. Then Eduardo said, 'You convinced me, man. Lucille the seal. Why not?'

'And what about the accent?' Roland went on. 'It says here that the legends come from Scotland, Ireland and the Faroe Islands in the Norwegian Sea.'

'I don't think she's Norwegian,' said Kylie, 'but Scottish or Irish seems right. Okay, so she's a selkie, maybe. That still doesn't tell us what to do about her.'

'Sure it does,' said Roland, bundling the book into Kylie's arms and getting to his feet. 'Egon must be done talking to that manager person by now,' and he made his way to the staircase.