In the prologue, Bone is the cat who meets Tigerstar and Boulder at the edge of BloodClan's territory, and the one who challenges them when Tigerstar visited Twolegplace to make the deal with Scourge that brings BloodClan into the forest.
Later, when Firestar visits Ravenpaw, Barley, who was in BloodClan as a younger cat, mentions briefly that he knew Bone, and says he is brutal. He also says that Bone wasn't much of a deputy, and Barley makes it sound as though Bone was more of a willing cat who carried out Scourge's dirty work.
During the battle between LionClan and BloodClan, Bone kills Firestar's aging deputy, Whitestorm. After this, he is attacked by a swarm of apprentices from all Clans, distracting him long enough to give Firestar time to say his last goodbye to Whitestorm.
However, Bone isn't able to defeat the apprentices, and the massive deputy has no chance of success. Within moments, he gives up the battle for life and dies under the claws of the swarm of the angry young apprentices, Ashpaw, Featherpaw, Stormpaw, Bramblepaw, and Tawnypaw, who are avenging the death of Whitestorm.
Bone is the so-called unofficial deputy of BloodClan, and Scourge's cat of choice to do his dirty work, but is quite often mistaken to be leader, due to the small size of BloodClan's leader, Scourge.