Diablo II/Search for Cain

The third quest from the Rogues is given to you by Akara after killing Blood Raven. She explains to you the magnitude of evil which you are facing in your journey and suggests that a Horadric Mage, named Deckard Cain would prove to be a powerful ally. Akara believes that Cain resides in Tristram, and that the quickest way to the city is through the use of the Cairn Stones in the Stony Field.

Stony Field
Akara will send you off to the Dark Wood to find the Tree of Inifuss which holds the answer to the Cairn Stones. First off, head to the Stony Field, you should find the Cairn Stones there but do not approach it yet, ignore it and continue to find a cave called The Underground Passage Level 1.

Rakanishu
Super Unique Carver (Lightning Enchanted Extra Fast), a Fallen guarding the cairn stones

Underground Passage Level 1
You will find considerably stronger monsters in here, particularly more corrupted rogues. Once you pass through the area, you'll find yourself in the Dark Wood.

Underground Passage Level 2
Optional

Dark Wood
The Tree of Inifuss is fairly hard to find considering Dark Wood is a pretty big area. You'll know when you find it if you bump into a unique monster called Treehead Woodfist (a Wendigo) followed by two of his minions, kill them if you can and speak to the tree in order for it to drop the scroll.

Treehead Woodfist
Super Unique Brute (Extra Strong Extra Fast), a Wendigo guarding the Tree of Inifuss

Once you've obtained the scroll, you can either use a Scroll of Town Portal or the waypoint here to return to the Rogue Encampment. Speak to Akara there to receive further instructions. Be careful, if you have not activated the waypoint, you will have to travel underground again to return.

Tristram
Akara will tell you to read the runes on the scroll. Do so by right-clicking on the scroll and you'll realize numbers would appear on the stones in the scroll. If you've seen the Cairn Stones in the Stony Field, go there now. If not then explore around until you find stone-like structures on your map. Click on the stones in the order shown on the scroll and a red portal to Tristram appears.

Once you enter, you'll realize that the whole town has been obliterated and is currently being occupied by monsters. Stay away from the dead cows in the area unless you don't mind taking damage. Deckard Cain is right in the middle of town, simply click on Cain's Gibbet to free him but be mindful of the monsters around you.

Griswold
Boss (Cursed)

Remember Diablo I? Well you might find ome familiar faces here, it seems that the blacksmith Griswold has succumbed to the evil much like Blood Raven had. Well to make things short, Griswold has enhanced strength and has a ridiculously high stamina to boot. Take him down for good item drops and to prevent him interfering with your mission, it may take a while however. Once you've taken down everything here, you might want to find Wirt who apparently is killed in the attack. Click on the corpse to receive lots of gold and his leg, which acts as an ordinary club. Keep this item until the end of the game to find an interesting little secret.