‘Phosphorous,’ says Lisa.

‘This is a cave,’ says Angela, as they emerge into the first antechamber.

Low in the wall, recessed shelves sit like catacombs, or votive alcoves. Electric sconces cast a dim light through the passageway. Chambers loom out of the dark, studded with shells from floor to ceiling in patterns of trees and flowers, stars and suns. The sharp edges of mussel shells fan outwards.

Tracing their way around a circular channel, the girls edge past a slightly plump child and his middle-aged parents.

‘This definitely isn’t it,’ says Angela.

‘But it’s pretty cool, huh?’ says Lisa, flicking on her lighter to examine a wall.

They complete the loop and step into a cavern hall, complete with altar.

‘The place of sacrifice,’ says Lisa, taking a photo.

The boy and his family enter the room.

‘Crazy shit,’ says Lisa.

The mother looks at them in annoyance.

‘D’you think they get bats here, at night?’ says Lisa.

Angela shrugs. ‘How would they get in? This isn’t it. Let’s go.’

‘Oh come on. It’s fun.’

‘It isn’t fun. I didn’t want this. I wanted to see the shell house.’

‘You must have misremembered it.’

‘I didn’t! I didn’t misremember it! I didn’t imagine it.’ Angela is starting to shout. The sound bounces off the walls.

‘OK,’ says Lisa. ‘OK.’

‘What are you looking at?’ Angela shouts at the boy’s parents. And then, at Lisa, ‘I remember. I was there.’

‘OK.’

‘It was a little old lady’s cottage. Every surface of the house and garden covered in shells, and garden gnomes made of shells. She’d done it all herself.’

‘It sounds lovely.’

Angela starts to sniff. ‘I bought a shell ornament there. An owl.’

‘Do you still have it?’ asks Lisa.

‘No,’ says Angela, with a sob. ‘I don’t have it any more.’

Another visitor enters, looks at the tableau, and leaves again quickly.

‘We’ll find the shell house,’ says Lisa, patting Angela’s back and trying not to look at the family. ‘The woman on the desk will know.’

Upstairs the woman’s eyes dart from Lisa to Angela, Angela to Lisa, Lisa to Angela. She doesn’t know about a shell house. This is the Shell Grotto, the only one. Lisa thanks her and they go, Lisa pushing Angela out of the door.

Outside, she says, ‘Are you sure it was Margate, Angela?’

‘Yes it was Margate! I was in secondary school when I last came, in my first year. A girl from school came with us.’

‘Would she remember?’

‘We’re not in touch.’

They walk back along Dane Road and into King Street.

‘What about your family? They’d know.’

Angela looks up. ‘My brother. He’d know.’

‘Shall we call him?’

In a urine-smelling phone box on the seafront, Lisa holds the door open while Angela dials home, a stack of silver change on the ledge in front of her.