Attack on Titan, Volume 16 of 34 (by Hajime Isayama)

(W) Hajime Isayama, Ryo Suzukaze (A) Satoshi Shiki
From Kodansha Comics. The prequel to the number one bestselling Attack on Titancontinues! "Keep Your Friends Close": As the days dwindle before the Survey Corps' last chance at an expedition, the need to train with their new equipment for fighting the Titans is more pressing than ever. But when an accident during training is revealed to be a work of sabotage, it sends shockwaves through the camp. Who is trying to ruin humanity's best chance at stopping the Titans, and why?!