Issues #6-#9 of Isle of Elsi Adventures will collect the 113-page story "R.J. Jr. in The Underground Underground" by Alec Longstreth. If you are interested in ordering all four issues in one fell swoop, you can purchase this bundle which also saves a bit on shipping costs.
This bundle was previously a "pre-order pack" where each issue shipped out one at a time as they were being published. At this point, all issues are in print and will ship out together as soon as I receive your order!