Steal an Artifact from Noble

"Lord and Lady Silvermoon have come in possession of a magical artifact. I need you to retrieve it," Nightingale says.

"What does the artifact look like?" You ask.

"It's hidden in a chest in their vault at their estate," Nightingale says, "You'll need to steal it without raising the alarm. There will be a party in two days that will be the best time to strike."

You think about the situation for a bit. Classic stealthy video game style you could go in like a ninja and steal the artifact... or you could think of another way. Perhaps pretend to be someone else or get in another way.