The Echo Protocol. The Umbral Spire, #2

After uncovering the true nature of the Haze Mantle and the sinister motives of Verrin Malcrye, Marrow Trask is no longer a passive observer; he is a rebel. Now a fugitive, Marrow must race against time to stop Malcrye from using the Rewriting Apparatus to erase the city's history completely. With the help of an unlikely resistance cell known as the Echoes, Marrow learns that the secrets of the past are hidden in plain sight.
Using a forgotten technology called the "Echo Protocol, " Marrow and Silra Kene must decode the memories of the city itself, racing to find the lost knowledge of the "Solmurmur, " a mythical hidden flame that could be the key to destroying the Umbral Spire and its oppressive gloom. But as they get closer to the truth, Marrow realizes that his own memory is the final piece of the puzzle, and that Malcrye has been playing a long game.