Mirkwood: Search for the missing wizard Radagast
Run ahead and then right. After a while on the left some orcs will appear - an archer (he's standing on the rock), two ordinary warriors and one heavy-armored. Kill them all. There is a heap of items under the rock where the archer was standing. Go forward in the direction of the glowing portal and you'll notice more enemies.
There will be two heavy-armored warriors, an archer and one ordinary warrior. In a moment another warrior, archer and heavy-armored warrior will join then. The sooner you get rid of the first group of enemies, the easier it'll be to deal with the second.
Keep going further. Several heavy-armored warriors will appear on your way, though not all will join the fight at once. Also, watch out for a few warriors who will appear to the right. It's not going to be easy here, so don't hesitate to use Beleram's help to kill some of the heavy-armored enemies.
Three archers and a heavy-armored warrior will join at the end of the fight. Defeat them all. You will notice some foot tracks (if you play as Eradan) and a heap of items. The traces don't lead to any secret, but they show the path to the place where you can do a side quest, so follow them.
Pass under the great tree. You will find another heap of items on the left nearby, while near the entrance to orc camp is the next one. Be careful, as a difficult fight with a large number of warriors and heavy-armored warriors awaits you here. Apart from that there will be several archers on the elevation in the camp. New enemies will be coming during the fight. You will also receive [SIDE QUEST] The Captive after a while. It's the [SECRET 1/4 for everyone].
Before you enter the camp, focus your attention on a great tree on the left, under which you can pass (there are mushrooms next to it). Do it and you'll reach two plants (one is closer to the left and another further on the right) and the chest that you should search. Return using the same path and turn left to run into the orc camp.
There are a lot of barrels and chests you can destroy in the camp. Search all you can - if you didn't acquire the Black Pearl earlier ([SIDE QUEST] A Gem No Mine Can Yield), then it's likely that you'll find it in a barrel or chest right here.
Run to the end of the camp to free a prisoner. On the left there is a heap of items and on the right a flower. Talk from Glorihirin, and you'll unlock the [ACHIEVEMENT] Friend of the Woodland Realm. After destroying all barrels and chests come back by using the path you already know to the place where you decided to follow the foot tracks (not the ones that were leading to a crate by the orc camp, but those you saw earlier). You must be careful, though, because when you reach the tree, under which you can pass, three heavy-armored warriors and three archers will attack you.
Pass under the tree and turn right. Search a heap of items and run further (on the right there will be a mushroom). You will reach the fork. The path on the left leads to the place you've already been to. The one opposite will take you to a heap of items and a mushroom, while the one on the right leads to the further part of the level.
Run following the right path. On the left and right there are corners with orcs. There are a few heavy-armored and ordinary warriors here, and a bit further - one heavy-armored and two archers (there's yet another archer on the left). The enemies won't all start fighting at once, which will make it easier for you to defeat them.
In the corner on the left there are two mushrooms, while the one on the right has a heap of items. You should also observe that the stone wall in the tree on the left can be destroyed - it's the [SECRET 2/4 for Farin]. Inside you will find some mushrooms and a chest that can be searched.
However, it's not all. Under the tree on the left there's [SECRET 3/4 for Eradan]. Yet, there is a problem with switching between the characters. You can use the save point described in the paragraph below and (assuming you play as Farin and you broke the wall under the tree) choose Eradan and return to a hiding place under the tree to find the secret. Finish the level using this character and then switch to Farin.
Run forward. There's a mushroom on the right, and a little further on the left there's a heap of items. Use the glowing portal to pass to the further part of the level - the game will be saved automatically. Follow the only possible path ahead until you reach to a place with cobwebs.
There's a plant on the left but before you collect it, defeat a swarm of small spiders and two bigger ones. You shouldn't have any problems with this battle. Before you go to a larger glade search a heap of items on the right.
Prepare for a lot more difficult battle with the spiders. New groups of small spiders will be joining the fight all the time, as well as individual larger spiders. Try to fight in the passage between the glades so that your opponents will have a difficulty with surrounding. On the left there is a heap of items.
If you look at this glade while standing right in the entrance to it, you'll notice two rocks near to each other. Run between them playing as Eradan and look at the left one's right side. In the rock there's a hiding place with items. It's the [SEKRET 4/4 for Eradan].
Choose the path on the right after you've searched it. You will defeat a small group of spiders (a lot of small and one large), and you will find a heap of items on the left. Run ahead till the end and you will find the next heap and a chest you should search.
Keep to the right corner of the map on your way back. You will defeat the last group of spiders (a lot of big ones and one smaller) and you will find a passage leading further. It will take you to the glowing portal. Using it will finish this level.