the heat
1. Central heating. Don't leave the heat on all night, or our energy bills will go through the roof! It's freezing in here! How long has the heat been off?
2. slang Intense police activity or pressure, especially following some crime. Tom's going to have to hide out until the heat is off. Could be a couple of months.
3. slang The police, collectively. The heat is showing a heavy presence in anticipation of the protests.