For most of its first season, Sugar on Apple TV Plus was a fairly typical if slickly produced detective story. It starred Colin Farrell as John Sugar, a private investigator with a number of charming quirks — obsessed with old movies, unable to get drunk, beloved by dogs — who was determined to solve a missing persons case involving the granddaughter of a famous Hollywood director. Then, at the end of episode six, the show introduced a twist that threatened to change it into something very different. But now that Sugar’s finale is out, it’s clear that the twist didn’t alter what the show already was — it just added some new flavor.

Spoiler warning for the first season of Sugar, including the final episode.

Okay, let’s get it out of the way: Sugar is an alien. At the end of episode six, he revealed himself to be a blue humanoid who looks like a cross between Doctor Manhattan and Nebula from Guardians of the Galaxy. It was a startling moment, although one that makes a lot of sense in retrospect. All of those quirks could be explained by Sugar’s extraterrestrial nature. He loves movies because he used them to learn about humanity. He can’t get drunk because he has different biology. And he’s part of a secretive group of polyglots because that’s how his alien friends meet up to discuss their observations.

Turning Sugar into an alien doesn’t fundamentally change the show — it’s still a modern noir with a compelling mystery at its core. The finale drives this home, as the sci-fi aspect mostly recedes to the background, while Sugar races to rescue Olivia (Sydney Chandler) from a potentially horrific fate and return her to her grandfather (James Cromwell). The episode is concerned with the same questions that have propelled the series since it started: what really happened to Olivia, and can Sugar save her?

Mostly, the sci-fi elements add to the urgency. In Sugar’s finale, the aliens are discovered and forced to leave Earth. This means that Sugar needs to solve the case before hopping on a spaceship to wherever he’s from. Every moment counts. And the show ends in a way all good detective thrillers do, with a crime that is disturbing but also isn’t quite the end of the story. Even if you guess where it’s going, there are a number of unexpected twists and turns along the way.

Ultimately, the aliens are a fun twist on a well-worn archetype. Sugar is patient, observant, and dedicated, skills that make him great at his job and that can also be linked to his extraterrestrial origins. He’s patient and observant because his real job is watching people and reporting back to his home world. He’s dedicated to finding Olivia because he experienced a tragic loss on his planet and doesn’t want it to happen again.

The finale also makes it clear that Sugar’s story isn’t over. He ends up staying on Earth, partly because he can’t get enough of humanity, but mostly because he discovers that a fellow alien — who has also stayed behind — is essentially the intergalactic Moriarty to his Sherlock. If it gets renewed, Sugar will likely shift from a detective story to a revenge tale. Hopefully, if that happens, it can maintain that careful balance between sci-fi and noir. Sure, Sugar is an alien — but that’s not the most interesting thing about him.

Sugar is streaming now on Apple TV Plus.