Neuvilette and Furina both work together as detectives. To investigate a case, they had to take a train to a city about 3 hours away.

When the two sat down in an empty train compartment, Neuvilette looked at Furina with an emotionless look and seemed to know that she would not stick with the case

N: "Furina, please do me a favor and take the case seriously."

F: "I always take the cases seriously, you just don't notice-"

The lights suddenly went out and the train stopped