DD's friend (aged 10) turned up on the door step a 4:45 and told me that she and DD had arranged to go Trick or Treating at 5pm which was news to me.
I'd only just got in and DH was collecting DD from After school club as it's on his way.
I got her to wait as as I spoke to DH who was at the school and said they would be back soon.
I had a quick word with DD as didn't want to tell her off infront of her friend (we'll have more words later).
It was 5:30 before they were in their fancy dress and left, DD's friend said she had to be home for 6pm and I said I'd take her.
DD called me on her mobile to ask me what time it was at 5:45 and I said they had another 15 mins. (I have now set the time on her phone).
They weren't back at 6 so I called DD, there was no answer but they were back at 5 past.
I drove the friend straight home and was there before 10 past. I went with her (thank God) to apologise for being late though it wasn't my bloody fault but the house was deserted, no lights on and no reply.
She went round the back but it was locked. She said she thought her Mum might have taken her brother trick or treating but wasn't sure and her Dad was at work.
DD's friend is a young 10, doesn't have a phone, doesn't know her parent's numbers. I left a note but her Mum doesn't speak English and her brother is only 7 - how's that going to work? 
IABU to be pissed off?