 Bornstellar is called to the Forerunner Capital to testify against the Master Builder, who has been put on trial.He stands accused of crimes against The Mantle, a Forerunner philosophy that values the preservation of life over all else.Just as the trial is about to begin, the Forerunner artificial intelligence Mendicant Bias, betrays the Forerunners and attempts to assume control of the Halos and use them against the Capital.