The Ruined Temple is a rather small dungeon, compared to the other dungeons in the area. On the Automap, it should become pretty easily seen soon after entering the temple. The Tome is guarded by a Unique Corrupt Rogue boss called Battlemaid Sarina. The Ruined Temple is located in the Kurast Bazaar. It will not be found in any other dungeon, so the player has the option to skip exploring the other temples. Lam Esen's Tome can always be found within the Ruined Temple in Kurast. It's rumoured it still remains, hidden somewhere within one of the temples in Kurast. This Black Book was lost when the misguided Zakarum took over the land, believing it to be filled with blasphemous heresy. Lam Esen, a sage of old who studied Skatsimi magic and the effects of the Prime Evils on the mortal world, wrote his findings down in a magical Tome. The quest is completed after players return Lam Esen's Tome to Alkor, who will then reward the player with five free attribute points. It's initiated by talking to Alkor after completing the Blade of the Old Religion quest and after having entered the Kurast Bazaar, or simply by entering one of the six temples in the Kurast Bazaar, Upper Kurast and the Kurast Causeway. Lam Esen's Tome is the fourth quest of Act III. The Black Book is much sought after by both good and evil.'' - Alkor

Quest icon 'The Black Book contains powerful secrets of Skatsim, the Old Religion, long eclipsed by Zakarum.

Diablo 2 act 3 quest 5