It's a sink-or-swim mission when Luke and the team dive into deadly waters to stop a sinister terrorist from making a massive splash.

As Greta attempts to loosen Luke's lips, the safe-house gang gets an earful from afar. Emma turns heads on the dance floor with an unlikely date.

While Cress tightens the screws, Chips matches wits with an interrogation expert. A stealth mission makes a bigger bang than expected.

Barry hitches a ride to the final frontier. As an operative's cover story begins to crumble, Luke and Emma seek help from an unexpected ally.

Every second counts as the team scrambles by land, air and sea to avert a catastrophe. Aldon finds himself outnumbered — but not outmatched.