Find this mission in Manhattan after completing Helicarrier Clean-Up. No more incoming calls from Nick Fury, now he just shouts at you from a street corner.
You'll need to find four wayward agents, and beat up whoever is threatening them. First, some Hydra goons just outside the Mansion.
Then some convicts on the Medieval shoreline.
Some escrima Jedi on the modern end of the Brooklyn Bridge.
And some mummies in Hydra Central.
When all four are safe, return to Fury to complete the mission, and unlock him for purchase.