Espionage Headquarters gives you the ability to spy on other countries or protect yourself from being spied on.
To spy on your enemies - select the province you want to put the spy on, and decide between Intelligence, Economic Sabotage and Military sabotage spies. Recruiting a new spy costs 15.000$.
To protect yourself - select the province you want to protect and assign Counter Espionage spies.
Spies on a mission will perform their mission and get paid once a day and can get caught.
There is no limit on how many spies you can put on a province.

Spy Types
Counter Espionage spies - counter and reveal enemy spy activity on your territory and cost 1,000/day per spy.
Intelligence spies gather information about the enemy's diplomatic relations and economical activities.
Intelligence spies cost 2000/day per spy.
Economic Sabotage spies damage the morale in the province they're put in, as well as destroy resource production.
They cost 4000/day per spy.
Military sabotage spies try to interfere with the enemy's military plans and infrastructure.
They cost 4000/day per spy.
Idle Spies hang around headquarters doing nothing and cost 500/day per spy.

Instant Actions
Instant actions are espionage missions that can be executed immediately.
Reveal Armies - Reveals armies in and around the province the action was executed on and costs 750 Gold.
Country information - Discloses the players resources, communications, spy positions, factory productions and diplomatic relations and costs 750 Gold.
Decrease Morale - Decreases morale in the province by 10% and costs 2.000 Gold.
Destroy resources - Destroys part of today's resource production in the province and costs 2.000 Gold.
Damage Upgrade - When executed, it damages a building in the province but never the capital, and it costs 2.000 Gold.