Basic human interaction operates along many of the same lines as international diplomacy. Sure, the stakes are a little higher in one, but from the average individual’s perspective, the tact and skill with which they handle someone’s personality – and the way they themselves are handled – is really all that matters.

As it demonstrates in what may be the series’ most nuanced episode to date, The Bridge investigates how the differences in interpersonal communication can be all that divides two or more people, or the very thing that brings them together.

So far, the series has illustrated a large world divided up into tiny subdivisions of race, class, gender, victim, perpetrator, etc. But in ‘The Beast,’ there begins to be a real breakdown and reclassification of character in a sense of their uniqueness – a reveal of things heretofore unknown, or unspoken about an individual that makes them who they are and illustrates that fact to those around them more distinctively.

In that sense, the complexities of international diplomacy have nothing on the delicate intricacy of human interaction. For starters, unlike nations, humans don’t come with a map clearly designating things like borders and boundaries, areas of great importance or sections that are better off left alone. In terms of discovering another person’s limitations and margins, most of us are blindly fumbling about, hoping desperately to comprehend the particular rules and regulations, codes of conduct and interpersonal policies without so much as a guidebook or simple information pamphlet to lead the way. Sometimes, it all goes smoothly; sometimes it’s trial and error; and sometimes, as it seems to be with Sonya Cross, it’s just about barreling through a situation and dealing with the ramifications on the other side.

The manner in which the show tests and examines these boundaries – within the framework of an ongoing murder investigation that is rapidly becoming more bizarre and perplexing – has so far been the cornerstone of what is essentially an increasingly compelling and satisfying character study.

Testing boundaries early on, Sonya shows up on Marco’s front porch to talk specifics of the case, but winds up having Sunday dinner with the Ruiz clan. As far as potentially calamitous social interactions go, Sonya spends her time deflecting and then calling out Gus’ goatish stares from across the table, giving Alma’s cooking the Chopped treatment with an Alex Guarnaschelli-like frankness, summing up her impressions of the meal with “it doesn’t taste very good,” and, finally, drawing a clear line from Marco’s missing and now-returned wallet and the woman on whose floor it had previously been left, putting her temporary partner at odds with his wife.

But Marco’s time in the doghouse does more than leave him with bloodshot eyes and the telltale signs of a police station bench on his slept-in clothes; it winds up being the key to breaking down a particular boundary that lets Sonya (and, less positively, Kitty) into the land that is Det. Marco Ruiz. Marco’s not just a surprisingly congenial Juárez homicide detective; he’s also something of cad (as far as Gus and Alma are concerned), someone for whom infidelity comes easy and admitting it to his partner is handled in the same matter-of-fact tone in which he chastises them for (however inadvertently) not having his back.

In this sense, The Bridge has demonstrated a surprisingly blunt form of character building, but through it all, the solid procedural elements at its core keep on ticking with great precision. And in that regard, the killer continues to elude capture, but his killing of a not-so-innocent Agent Gedman last week suggests the motivations behind the slayings go beyond the already hefty themes of social and racial awareness along the El Paso-Juárez border, straight into the idea of governmental and institutional corruption and their complicit side-stepping of embarrassing agent-related scandals.

Meanwhile, mumble-mouthed Steven Linder does his ironing and killing of home invaders in a manner of dress not too dissimilar from Walter White during his nascent meth kingpin days. Despite a noisy pre-dawn disposal of Hector Valdez’ rug-wrapped body, Linder appears to have gotten away with his (potentially justifiable) homicide, only to end up face-to-face with another kingpin looking for some restitution for the loss of his property.

This understanding and balance of who people are when it comes to their lives at home or at work, and the question of what they are willing to share, offer or sacrifice (which is very little, in regard to Daniel Frye), is what ‘The Beast’ superbly demonstrates. And even though it also takes on the additional weight of introducing two new characters – Brian Van Holt (Cougar Town) as a mysterious acquaintance of Charlotte’s and Cole Bernstein as Gina Meadows, a troubled young girl whose ill-advised trip to Juárez turns into a string of increasingly shocking encounters – the exploration of the importance of boundaries, both personal and geographic, remains strong throughout.

The Bridge continues next Wednesday with ‘ID’ @10pm on FX.