"How To Recognise An Alien"

• They have no pulse or heartbeat
  
• They need to regenerate themselves at regular intervals otherwise they die
  
• When they die, they incinerate, leaving virtually no trace
  
• Some of them have a mutated fourth finger
  
• When they are wounded, they don't bleed
  
• Pure Oxygen is fatal to them
  
• They have no emotions

"They need to regenerate every few weeks to retain their human form"

"I've discovered an alien regeneration station"

"Have you ever seen X-rays like that?"

"Some of them have an awkwardness about their hands - a mutated fourth finger"

"Scoville Electronics"

"I believe the newspapers call them 'Flying Saucers'"

"I spent a year in UFO investigation. There are a lot of unsolved mysteries"