Tragedy in the Rain

Tragedy in the Rain (雨中の惨劇) is the 4th and final chapter of the 16th volume and the 60th chapter overall of the Attack on Titan: Before the Fall manga, written by Ryō Suzukaze and illustrated by Satoshi Shiki.

Overview
Thirty minutes prior to the red flare being sent off, Carlo Pikale and teams one through eight approach the farthest mapped point outside the Walls. When the rainfall begins once more and threatens the expedition, an unlikely person forces them to continue on. Meanwhile, teams nine and ten come upon a discovery that forces Rosa Carlstead to make her first major decision as Team Leader.

Summary
Carlo, Xavi and teams one through eight approach the edge of the charted territory at an oasis ten kilometers beyond the Wall; Carlo orders they wait there while sending teams three and four ahead to scout the area. Xavi notices that Carlo is behaving cautiously and is informed that the oasis is a perfect hiding spot for both humans and Titans, with blind spots located everywhere. Carlo then notices that storm clouds are returning; with rainfall imminent, he decides to have the expedition aborted. Xavi reminds him that this will lead to the Survey Corps being dissolved; Carlo reaffirms his decision to not place the lives of his soldiers in danger due to the unknown.

Just then, a red flare is fired in the distance of the oasis alerting them to Titans nearby. Carlo orders the soldiers to regroup and ultimately return to the first oasis. Xavi suddenly rides towards the direction of the red flare and Carlo orders him to fall back, to no avail. He then orders his soldiers to follow their orders and goes to chase down Xavi. At the same time, rain begins to fall again and Carlo begins to question whether it was smart to send teams three and four ahead (along with choosing to undergo an expedition at all with poor conditions). He then brushes aside those concerns and tells himself to focus on the task at hand.

As team ten begins to panic over losing sight of the red flare, Kuklo asks Rosa what they should do. At this time, team nine rides to their location and the two teams decide what to do next. Captain Simon Barna mentions that he knows the territory and muses that the flare came from the farthest oasis in the south. As they travel past the halfway mark, they come across the ruins of a munitions wagon; Kuklo and Cardina go to investigate and proceed to call the others over. The wagon is revealed to be from team 7 and 8 and that both have been wiped out by a roughly ten-meter Titan; Kuklo believes it to possibly be the one Cardina and himself encountered back in Shiganshina. Barna asks Rosa whether they go fight the Titans or retreat. After a long moment, Rosa decides to continue on with the mission and orders them to proceed ahead towards the oasis.

As Xavi reaches the ten kilometer oasis, he glances back at the rest of the soldiers in the expedition and journeys into the forest there. Searching for a trace of the red signal flare, he hears a rustling nearby; reaching a clearing, Xavi is horrified to spot the missing leader of team eight in the process of being devoured by a Titan. Noticing Xavi's presence, the Titan finishes devouring the deceased soldier and peers down as Xavi warily grasps his sword.