Speak to Madame Hydra on the streets of Hydra York to learn of her staffing woes.
She's looking for someone in a very particular costume. She even has a picture.
Retire to Mansion's Customizer, and gin up a character who fits the bill.
Return to Madame Hydra to begin your mission. You'll mostly be fighting mummies.
They're not dangerous, but they can soak up hits. Beam weapons can be a good way to neutralize and destroy them.
When you've beaten the third and final wave, Dig up all the dirt piles, then smash the unearthed treasure chests to free Madame Hydra's precious snakes.
Completing this task completes the mission, and unlocks Madame Hydra for purchase.