Another expression would be the heart of the matter. A spiral is a curve winding around outward from a central point. Spiraling numbers means numbers that are increasing fast. On time means not early and not late. In the example sentence, either could be used.
Law enforcement means causing a law or rule to be obeyed.
The police are responsible for law enforcemnet. And finally, covert, which means hidden or secret. And another word meaning secret is clandestine. That clandestine organization is engaged in covert operations at home and abroad. If I say that money has dried up, it means that it isn't there anymore.