In 1775, Joshua was part of Adam Crais' militia. He and the rest of the soldiers were hiding in the Drowning Cave, when the Black Door revealed itself. Harm Timmerman became possessed, and attacked the soldiers. Joshua Locke was killed, though his efforts to restrain Timmerman reportedly saved many lives.
His fate was later explained to Benjamin and Miranda, who were distraught when the learned they had lost their brother.
Benjamin accidentally summoned his soul with the Echo Key.