From the Module Description and Publisher's website:
“Stick in the Mud” is a short adventure for five 1st-level characters that takes place in the Chaos Scar, near the King’s Wall. It pits the
PCs against a tribe of evil bullywugs that have taken up residence in a long-ruined keep. The keep, once the abode of a goliath sorcerer,
holds a powerful magic item, the staff of earthen might. The staff has been damaged and is hemorrhaging magic. This leak has ripped
open a small portal to the Elemental Chaos. A tide of mud has been steadily flowing through the portal and into the cellars beneath the
ruins, creating a muddy wallow that is ideal for bullywugs.