FX’s ‘Most Dangerous Animal’ Explores an Unexpected Story Through Zodiac Legacy

It’s fairly easy to become obsessed with the Zodiac Killer. There are only a handful of cases like it in the last 50 years. The infamous serial murderer terrorized the San Francisco area in the late 1960s and early 1970s. He killed at night in deserted lovers’ lanes. He killed in broad daylight. He killed in a populated neighborhood. He threatened to shoot children coming off school buses. All of it bragged, foreshadowed and confessed via letters and detailed cyphers to local newspapers. And he was never caught. The unknown breeds obsession, and the lack of a fully identified killer drove thousands to relentlessly focus on finding the killer.

FX’s docuseries The Most Dangerous Animal of All starts with an obsession, but not the one you’re thinking. It introduces Gary Stewart, a man given up for adoption as an infant who continues to struggle with identity and abandonment issues well into adulthood. But his obsession in finding his birth father takes an unexpected turn – Stewart believes his father to be the infamously unidentified Zodiac Killer. Based on his book of the same name, the 4-part docuseries explores Stewart’s research and lays out his case effectively and efficiently. Yet, it’s a shocking fourth act that elevates the material to something incredibly fascinating.

Dangerous is about the Zodiac Killer and the paranoia around San Francisco during his reign of terror. But it’s also not about Zodiac at all. It smartly uses the Zodiac case to explore Stewart’s deeply wounded psyche. Stewart talks about his adoption, his family, his birth mother, and several other personal topics in a damaged, mournful voice. He frequently stops his train of thought to avoid a full breakdown during filming. Despite owning his own business and having a son of his own, the absence of a father clearly impacted the man in seemingly irreparable ways. As he lays out his case, Stewart carries you along with him thanks to his unwavering conviction.

The docuseries ultimately looks to explore the central question of identity. Was Stewart’s father really the Zodiac Killer? Or is all of Stewart’s evidence a circumstantial collection intended to build an identity – any identity – for someone he never knew? The result is an unforgettable documentation of obsession, one that becomes more cutting the deeper it goes.

The Most Dangerous Animal of All airs all four parts tonight on FX starting at 8 pm ET.