A man was killed in a roundhouse with no doors or windows. Four maids were present at the time of the murder, but are saying nothing. When asked what they were doing they replied as thus:
Maid 1: 'I was making the tea.'
Maid 2: 'I was dusting the mantelpiece.'
Maid 3: 'I was setting a mouse trap in the corner.'
Maid 4: 'I was watching the telly.'
One of the maids has lied. The liar is the murderer.
Who is the murderer and what is the lie?