When Harry reported that Voldemort had returned, towards the end of "Harry Potter and the Goblet of Fire", Dumbledore reactivated the Order. Many of the original members returned and were soon joined by recruits who effectively replaced those who had died in service during the first conflict. The Order established their headquarters at Number Twelve, Grimmauld Place, Sirius Black's family home, during the interval between the fourth and fifth books in the series. Dumbledore was the Secret-Keeper for the Order, meaning that only he could reveal the location of the Order's headquarters to others. Dumbledore's death in book six made the location vulnerable and it was abandoned in favour of The Burrow as a result.