Another bust is waiting for you in the sarcophagus (yellow dot). Go deeper into the corridor, kill the ghoul and use the lever (red dot). Talk with Olf and he'll give you the 3rd bust. Return to the chamber with the bars (white dot). Use the bust on the altar by the bars and do the same with the other two.
Pick up the nautilus transformation scroll at the green dot. Don't step on the floor marked with black dots, instead use the scroll and go through the hole in the wall marked with a blue dot. From the sarcophagus room, go into another one below (black dot). Turn left and climb the ledge.
Go further and you'll arrive at a big room with a hole in the ground. You should find yourself inside a building made of light bricks. Go to the ground level, through the door and you should see a lizard priest who's in possession of the disk you're searching for and, among other items, a teleport stone (eastern temple). Using the stone you can return to the temple entrance and talk with each of the bandits. They will share their loot with you. After talking with Maliko (M5.14) you can return to Fincher (M3.21) and give a report.
Cyrus is late
You will find Cyrus by Eldric's house, in M5.1. You have to search the house for a green druid sleeve. Under the table you will find a mana potion recipe. Cyrus is not willing to help, so go to the neighbours (M5.2).
Jasmin (M5.2), in return for 200 golden coins (buying her skins) will allow you to use her wolf pet - Rufo. If you don't have raw meat with you, buy it from her and feed the wolf. Afterwards make him smell the sleeve. Follow the wolf, attacking the monsters on your way - the wolf will stop four times in total. During the 3rd time you'll find a Druid's staff. By the 4th, you'll find the temple (M5.3).
Touch (stand and press) the magic barrier and return to Cyrus (M5.1). Lead him to the temple entrance and ask to get rid of the barrier. Use the destroy magic force field scroll, get rid of the obstacle and go inside. Deal with the lizardmen in the main hall and go right. There kill another enemy and take the map of the temple from the chest.