My protagonist, let's call her Alice, must acquire a priceless artifact, located deep inside an ancient temple.
If this were a ruin, the exercise would be academic, but the Temple was protected by the ancient and terrible power that built it. The only way in and out of the Innermost Chamber where the the artifact is located is through a vast spiral hallway. One's innermost thoughts simply reverberate across this long Hall like so many echoes. The priests protecting the place can hear these thoughts, and a single thought by the priests can activate the large golem army of statues that currently stand immobile across the length of the place.
There are always three priests in the Reverberation Hall listening for stray heretical or otherwise dangerous thoughts, each of which can activate the defenses. Only one pilgrim is allowed to enter at a time, and hall is so vast it takes 10 minutes to walk across the length of it. Along the way there are numerous mural images: admonishments to turn back if not pure of heart and purpose, depictions of thieves (covered in hay for some reason) being crushed by heavy golem fists, pilgrims worshiping the meticulously depicted artifacts in rapturous joy. There are representations of eyes everywhere, and they all seem to follow the pilgrim as she makes her way across the hall.
Now Alice does not have an army to assault the place (and frankly, I doubt the adamantine golems would be much troubled) but she needs to gain control of a particular artifact against the wishes of the priests. Since she has a replica, if she does manage to gain it and walk out, the theft would probably not be noticed for a long time, since the priests do not patrol or (out of respect) listen to the prayers and thoughts in the Innermost Chamber where the artifacts are.
How do I get Alice to gain the artifact, against the wishes of the priests? How do you avoid thinking that you are a thief, while, well, being a thief?
...well, besides the obvious way. :)
LATE EDIT: Thanks everyone for the very ingenious answers! @DanSmolinske had the most creative answer in my view, with the benefit of using elements from prior steps of Alice's saga as outlined here on Worldbuilding. @WhatRoughBeast's answer will definitely be blended in as well.