i am looking for a train please going to cambridge .
user
i would be happy to help with your request , to narrow it down where is your departure site and what time do you want to arrive ?
assistant
i am looking for a train leaving from london liverpool street after 20:00 on friday .
user
how about train tr8373 that leaves at 21:39 ?
assistant
its ok . book for 8 people and help me get the reference number please