'Gas!' said the Doctor, listening to the hissing sound coming from beneath the door of the Oxygen Store Room.

Jamie was unable to answer.  He was almost overcome by a violent fit of sneezing.

The Doctor tried to open the door.  It was locked, with no sign of the key.  'Victoria!' he shouted, thumping on the door.  'Are you in there?'

Victoria's reply came almost immediately from the other side of the door.  But her voice was now faint and barely audible.  'Doctor...'

'She's in there!' yelled the Doctor.  'Come on, Jamie!'

'Doctor... help me...'

'We're coming, Victoria!  Hold on!'

The Doctor and Jamie folded arms, and stood back a pace or so.  'One... two... three!'  With one enormous effort they lunged at the door, which burst open immediately.

Victoria was lying in a heap on the floor of the Oyxgen Room.  Her eyes were half-open, and she could hardly breathe.

'Quick, Jamie!' said the Doctor, covering her mouth with his hand.  'Get hold of her!'

Jamie let out the most deafening sneeze, then helped the Doctor to lift Victoria and carry her out into the corridor.

'What's going on here?'  Robson's rasping voice boom out from the other end of the corridor.  'Who let you three out of the cabin?'

The Doctor and Jamie ignored him.  They were too busy helping Victoria to revive.

Robson came hurrying down the corridor.  Van Lutyens and the Chief Engineer were with him, but they went straight into the Oyxgen Store Room.

'Did you hear what I said?'  Robson was yelling again.  'I gave strict orders that - '

'Mr Robson!'  Van Lutyens, covering his mouth with his hand, was at the door of the Oxygen Room.  'In here.  Gas!'

'Then find out what it is.'

Van Lutyens disappeared back into the Oxygen Room.

The colour was gradually returning to Victoria's pale cheeks.  'It was horrible!' she said to the Doctor, still struggling to breath clearly.  'That awful creature.  What was it?'

The Doctor was immediately tense.  'Creature?'

'You... you didn't see it?'  She turned around to look back into the Oxygen Room.  'In there?'

The Doctor, Jamie, and Robson looked into the room.  It was now fully lit.

'It came... straight at me... an awful hissing sound... and foam... and it was covered in weed or something... oh, I don't know...'  Recounting her ordeal was clearly distressing Victoria.  Her eyes were wide with fear.  'It came closer... and closer.  Then I screamed, and...'  She covered her face with her hands, and dissolved into tears.

'It's all right, Victoria,' said the Doctor, holding her close in his arms protectively.  'You're quite safe now.'

Robson was glaring at Victoria cynically.  'Creatures indeed.  The girl's hysterical!'