Prince of Crime
After the events that took place after Batman's battle with the Court of Owls, the city quietened down.
On one rainy day, Batman knew a dangerous forgotten force was back in Gotham city. As predicted, the Mayor of Gotham city had been given a dose of a lethal chemical.
The only way to save the Mayor was to answer the question that had been written on the wall of the Mayor's office,
What is the value of constant volume heat capacity for the compound present in laughing gas?