Demian Bichir as Marco Ruiz in “The Bridge.” (Byron Cohen/FX Network)

I like “The Bridge,” FX’s show about an El Paso detective, Sonya Cross (Diane Kruger), who ends up partnered with Marco Ruiz (Demian Bichir), a Mexican cop from a corrupt department. But when the show, which conducts many scenes in Spanish and has a sometimes-keen sense of border politics, returned last week, I found myself thinking of “The Bridge” as a cautionary example of what can happen when a show tries to be topical.

In trying to capture the more dramatic crimes that can happen on a fluid border between two countries, “The Bridge” has been overtaken by the evolving immigration debate.

“The Bridge” is one of a number of dramas that might be more properly called horror series. Showrunner Elwood Reid and the directors he collaborates with have an eye for the eerie: a skeletal Madonna in the desert, a blank-faced lawyer in a 10-gallon hat carefully tucking his pants into his boots as he ventures into a new house that has been splattered with blood, the fascination in Cross’s eyes as she watches beetles clean a small skull.

Knowing how to turn out such images is not the same thing as knowing how to parcel them out for maximum impact and when to deploy them. In the second season of the show, the baroque criminality taking place on both sides of the border in “The Bridge” feels a bit like the new normal. When the news that a Mexican drug lord put in an order to have a dead Drug Enforcement Administration agent taxidermied fails to shock, a show has calibrated something wrong.

Against all of this, though, “The Bridge” still excels at generating outstanding moments of human interaction.

It is both funny and tremendously sad to watch Sonya awkwardly seduce the man whose brother murdered her sister, the sex that follows more a purge of grief for their ruined lives than an expression of lust. Daniel Frye, the addict and reporter played with tremendous verve by Matthew Lillard, and his lesbian Mexican partner, Adriana Mendez (Emily Rios), remain one of the most compelling duos on television, whether Frye is arguing with his Alcoholics Anonymous sponsor over the comparative merits of the band Rush or crashing Adriana’s dates.

The imbalance between these two strengths on “The Bridge” feels particularly strong because of what is actually going on at the border right now. The menace of someone like cartel boss Fausto Galvan (Ramón Franco) seems a little silly and over-the-top in contrast to the factors driving unaccompanied children north in numbers that have produced a humanitarian and political crisis.

“Gang violence in Central America, especially in Honduras and El Salvador, is driving a substantial exodus to other countries throughout the region,” explained Vox’s Dara Lind. “In particular, teenagers in these countries are being recruited to join gangs; if they refuse, the gang will often retaliate against them and their families.”

Lind reports that the children who are getting caught at the border are getting younger by the year, and more of them are female.

The prospect of parents sending their children on alone or of children making long journeys to reunite with their parents presents terrible tradeoffs. Is it worth risking sexual assault or other violence on the road to avoid being impressed into a gang? The idea that more than 50,000 children, traveling without their parents, have been apprehended trying to get into the United States so far this year, does not need the splashy addition of a serial killer or a cartel leader to be horrifying.

“The Bridge” can tell this kind of story, when it wants to.

I can taste the bile when raw terror rises in Maria’s (Karen Sours) throat even after the horrors she experienced as an undocumented immigrant were supposed to be over. The disappearance last season of Adriana’s sister, who works in a maquiladora, was as frightening as any of the more conventional horror scenes in “The Bridge.” Its characters are experiencing the large and small cultural transitions of the present moment in immigration policy, as when Marco corrects Sonya when she refers to an “illegal immigrant” rather than an “undocumented” person.

Unfortunately, “The Bridge” tries so hard to shock us into awareness that it forgets there are other, more humane ways to appeal to our senses. Maybe the show is following the logic of Washington, reasoning that our sense of fear is stronger than our feelings of compassion. If so, it is a depressing illustration of how static the dynamic of immigration enforcement and reform has become that even art does not trust itself to move us.

Alyssa Rosenberg blogs about pop culture for The Washington Post's Opinions section.