 Cole s demonic alter-ego Belthazor is in a desperate fix: having killed the triad which was about to punish his failure with vanquishing, the Source of evil himself has sent the bounty-hunting demon Krell at his trace. Since the sisters wounded him, he can only maintain his human form shortly and can t shimmer anymore so when a spell summons him to Prue and Piper, it s Krell who s transported, and convinces them to collaborate: he alone can track Belthazor, they can vanquish him. But it s Phoebe who finds him, and gets Leo to heal him, thus finding out he is only half human; her dilemma is whether to betray her sisters for love, or kill her lover...