Attack on Titan vol 5

Thanks to Eren, humanity has taken the town of Trost back from the Titans. Exhausted, Eren falls into a coma for three days - and wakes in shackles, staring at Erwin Smith, leader of the Survey Corps. Certain that Eren's father's research holds the key to the mystery of the Titans' rise, Smith wants an expedition to retrieve it from the house where Eren grew up. But that's deep in Titan territory, and to get there Eren will need to master a power he still doesn't fully understand.