Fliss went on a school trip near Whitby, England after a nightmare, she had the night before. In the nightmare she walked in the middle of the night into a scary house, where she was forced by her legs which she couldn't control, to enter the room 13 as she heard sound like "the room of doom" or at the gateway "the gate of fate".
When the class arrived and got to see the hotel Fliss became suspicious of a cupboard next to the room 12, because there was no number on it and when she asked the teachers they said that it's just a regular cupboard.
In the night Fliss was woken up by the sound of someone walking on the stairs and she went to the bathroom to see what's happening, then she found spilled water on the floor.
The next day the class went on a trip to the sea and in the break one of the teachers asked how everybody's night was. Trot said that he couldn't sleep because Ellie-May was sleepwalking on the stairs . After the break Fliss told Trot what happened to her the night and they agreed to see where she goes and meet by the 12th hour P.M. in the bathroom on the 3rd floor with their friends Gary and Lisa.
No i wasn't, lier
Bad, Ellie-May was creeping around the hotel
how was your night?
The next few nights Fliss and her friends Trot, Lisa and Gary were watching Ellie-May in the middle of the night her walking to the cupboard. They found out that on the cupboard the number 13 appears every night. When the friends decided to tell the teachers they thought that it's a joke and didn't trust them. One night the teachers found Fliss, Trot, Lisa and Gary keeping Ellie-May by force to not enter that room, because whatever was in there made her sick.
The last day on the trip Fliss and her friends went to a hounted house organised by adults. At the end of the house she saw a little hole she could go into and there she found Sal a creepy old person which was sitting almost all the time in front of Fliss's hotel, she told her story about a vampire living in that cupboard she was suspicious about and that she had to kill him to save Ellie-May and others who got cursed by the vampire and got sick and died. So as she said Fliss killed the vampire with a souvenir for her mom and with the help of her friends.