Located in a valley between the Borean Tundra and Arthas' home of Icecrown, the Sholazar Basin is a lush, tropical jungle that is a nice break from the frozen landscape that makes up most of the Northrend content to come.
You receive a quest in Dalaran to try and locate the missing legendary hunter, Hemet Nesingwary, who was on his way to Sholazar to hunt the ultimate game when he was last seen. You get a ride in by plane, but it is quickly shot down by Scourge winged demons. You survive by landing in a tree, and make your way to the nearby Nesingwary camp.
The settlers here are also stranded, so you help out by borrowing some supplies from a nearby strip mining operation.
This unlocks the flight plan in and out of the Basin, so you can come and go whenever you want.
Despite having met Nesingwary in both Stranglethorn Vale and Nagrand in the past, and performing multiple tasks to earn his praise, you are still subjected to the same multiple hunting quests in order to proceed here. Some of the quests are the traditional "Go kill a lot of animals. I mean like, 30 each..." style, and others have you reanimating the bones of a long-dead creature to find out where you might find the ultimate game in the Basin.
You eventually find out that the ultimate game is a fiery protodrake broodmother, so you and Nesingwary capture a mammoth mount, ride it into battle, and kill the drake.
The main threat in Sholazar Basin comes from its proximity to Icecrown. A giant glacier has overcome the northeastern part of the zone, and giant Scourge abominations are making their way in.
A Titan watcher, named Freya, has left her giant avatar near the Glacier to help protect it from the encroaching Scourge. She tasks you with seeking out the reason that the Scourge have been able to neutralize the Titan pillars which should have protected the area.
At a nearby camp, you find your answer. The Cult of the Damned, agents of Arthas, have been bombing the pillars in order to weaken the Basin's defenses.
Some of the pillars reach high into the sky.
Freya has a plan, however, and guides you to a massive gate in the southern part of the zone that teleports you to a matching gate in Un'Goro Crater, back on Kalimdor.
There, you encounter the Etymidian, a giant weapon created by the Titans, that you are able to control. You ride it into the Glacier, and are able to turn back the Scourge forces, and force them out of Sholazar Basin.