Their plan to capture the "driver" of the Aberrant Titan has failed, and now it looks like the Survey Corps will have to find a way to deal with this probably traitor in their human form as they set out to pursue Eren once again.
As if this pursuer wasn't deadly enough as it was, it seems that things are even more dire than anyone could have anticipated, as it appears that this individual also has the stamina and wherewithal to turn into their Titan form again. This leaves Eren's current escorts no choice but to beseech him to run while they try to take on this monster to at least buy him time to make good his escape - something that they prove to be hugely proficient at as they succeed in first blinding this Aberrant, then turning its tendons to mincemeat to prevent it from protecting its neck.
However, proficient still isn't good enough to take on this class of monster, and those fighting against the Aberrant soon see the true powers and abilities of the beast come into play, much to Eren's horror. It's this shocking vision that makes Eren decide that he was wrong to ever consider running considering his own titanic ability, and thus he wastes no time turning into his own Titan form to take on this enemy in a bout of epic fisticuffs. Unfortunately for Eren, his opponent is clearly more skilled in this form, and ultimately Eren is literally ripped from his Titan body and seemingly kidnapped. Perhaps the day isn't quite lost however, as Mikasa and Levi are on hand to join forces and give chase.
For all of the elements and moments you can point to that detract from this series as a whole, an episode such as this is a comprehensive answer to those still unsure as to why Attack on Titan is currently such a hot property. With its continuing twists and turns, compelling action, and an ability to leverage its characters and scenarios to such an extent that you end up spending half of this episode yelling "go on Eren, hit 'em!" at the screen (that wasn't just me, right?), this is simply fantastic viewing that you can't help but be gripped by every minute. It's great stuff, and once again I'm left on tenterhooks for what next week's episode might bring.