The main story in this volume, "Healing the Breach" (15-18) has some very interesting backstory on Alec (and Linda!) that strongly places them in a historical time period and that does a great job of characterizing them. It's also terrific to see a new character from their ancient past, something that's almost never been done in the Swamp Thing comic. Unfortunately, the present-day storyline of this story is almost entirely incomprehensible. There's a dead spot in the Gulf of Mexico and ... stuff.
The "Holland Mind" short (19) that follows is much clearer; in fact, it explains many of the plot threads going back to volume one, including a lot of stuff that was totally non-obvious previously, like the fact that Swamp Thing apparently lost his humanity again right after he gained it in the first arc of this series. The way in way Alec's humanity seems to be coming and going throughout this Swamp Thing series is frankly befuddling (and something that probably wasn't helped by the changing writing teams).
Sadly the last issue in this volume (20) is then another confusing mess.
And where are Abby and Tefe in all of this? Who knows! Swamp Thing's supporting cast appears to have been abruptly jettisoned.
Unfortunately, this volume as a whole is a half-baked mess that barely makes sense. Worse, it highlights the fact that this entire series is a half-baked mess, since it's apparently full of undercurrents that weren't obvious, and since it abruptly jumps from one thing to another. I wasn't unhappy to see it left behind and forgotten ... though I've always been annoyed that DC betrayed its Swamp Thing fans by not publishing the fourth and final volume of this series.