See my review of Isle of the Rat Wizard for conversion to various D&Ds
I'll be honest when I say I preferred the Isle of the Rat Wizard, but this little adventure should be thought of more as a great drop-in piece with the potential to be a Secret of Saltmarsh meets Secret of Bone Hill mashup. Seemingly fall-off-a-log-simple adventure with throw away plot, this little nugget could really be used well as the mate with IotRW, as they suggest in the beginning of W!HCtD. I even thought of running this one first and then placing the mcguffin for defeating the baddie in this adventure on the Isle of the Rat Wizard. The magic items in each are strangely, alluringly similar, suggesting a possible greater unseen whole.
Buy this and give it its due expansion and integration in your setting. Buy IotRW, too, and combine them.
Please pay these folks something, they are well worth your time.