Forgotten Realms: Demon Stone is a game with a story written by R.A. Salvatore about three adventurers who get involved in an inter-planar war.
Orc armies and the red dragon Caminus are raiding the Gemspark Mine in Damara. Three adventurers, Rannek, Zhai, and Illius take it upon themselves to save the civilians in the area and secure the mines. They join up and eventually defeat the warlord controlling the dominant army. Searching the area, they come across a mysterious stone and accidentally release the prisoners it contains: the Githyanki general Cireka and the slaad Ygorl. They summon their armies and resume an old fight.
Zhai takes them to her home, Cedarleaf, a wood elf village, only to find it under attack by Cireka's Gith. Ygorl intervenes, trying to steal Cireka's Silver Sword. The party escape to Blackstaff Tower to meet with Illius' mentor, Khelben "Blackstaff" Arunsun, who tells them that they need to go to a yuan-ti temple to Merrshaulk in Chult to find a demon stone that will re-imprison Cireka and Ygorl. Unfortunately, Ygorl shows up again vowing revenge and while the protagonists escape, Khelben disappears and Blackstaff Tower is reduced to ruins. The three find a portal to the yuan-ti temple and steal the demon stone.
They then go to Mithral Hall which is under attack by an army of trolls. They aid Drizzt Do'Urden and Clan Battlehammer in defeating the trolls and use the Underdark tunnels from the hall to get to an ancient Githyanki stronghold where they expect to find the two warring generals so that they can imprison them in the stone. Unfortunately, Ygorl sends them both through a portal to the dragon Caminus,'s lair. The dragon obeys Ygorl and kills Cireka, rendering the demon stone useless but Rannek takes Cireka's sword and slays the dragon in turn. Ygorl leads the trio back to Damara and then to Limbo and reveals that he manipulated them into joining together and bringing him Cireka's sword. They kill Ygorl and escape back to Cedarleaf where they find Khelben, unharmed. King Gareth Dragonsbane awards the three an area of "untamed land" as a reward.