From the publisher's website and the first page of the module:
“The Brothers Gray” is a short adventure for five 1st-level characters that takes place in the Chaos Scar, near the
King’s Wall. “The Brothers Gray” takes the PCs into the ruins of an abandoned mining outpost, where they must
contend with a trio of murderous halflings. If you’re not playing a Chaos Scar campaign, you can still use this
adventure by integrating it into any existing campaign situated near a wilderness area that had mining operations
at some point in the past.