The Final Problem Ending Explained: Who is the Killer?

Helmed by Félix Viscarret, Netflix’s ‘The Final Problem,’ also known as ‘El problema final’ in the original Spanish, takes a page out of the Sherlock Holmes playbook and applies it to a rather unique locked-room mystery. Benjamin Basil, a veteran actor perhaps best known for bringing the master detective to life on-screen, finds himself stranded in a hotel on the remote island of Santa Agueda when a woman is discovered to be dead. With about a dozen suspects in front of him, Basil has no choice but to put his detective hat on, this time for real, and deduce the truth that everyone seems to be missing. By its end, however, this murder mystery series, based on the eponymous novel by Arturo Pérez-Reverte, proves to have a greater emotional component than anyone could have guessed. SPOILERS AHEAD.

The Final Problem Plot Synopsis

‘The Final Problem’ begins with a glimpse into the life of Benjamin Basil, an aging actor who once took the world by storm with his portrayal of Sherlock Holmes. Now, years later, he gets offered a new role by an old friend, Fonseca, who, along with his lead actress, Vicky, plans to take Benjamin to the studio via his yacht. However, when the storm forces them to land on the island of Santa Agueda, there is only one place where they can stay, the luxurious Hotel Ausländer. The other guests currently residing there include a mysterious German couple known as the Klemmers, a detective fiction writer named Francisco Foxa, Dr. Seruya, and best friends Elisa Mander and Adela Figueroa.

As the guests get to know each other better, night falls, and the entire hotel goes dark. The next morning, one of the maids discovers the body of Elisa inside a room locked from the inside, with a broken rope hanging from the ceiling, and a chair lying flat. While everyone immediately assumes that Elisa killed herself, Benjamin, having trained himself in the ways of deduction, notices that there is no rope on her neck, among a string of other oddities. This leads him and writer Foxa to believe that a murder has taken place, and soon enough, the doctor on site, Seruya, begins acting suspiciously. Right before Benjamin can gain any information out of him, however, Seruya is found dead in his room, with the killer this time staging the scene with a sense of pride.

As fear takes over the hotel, the storm makes it harder for the owners to call the police. Benjamin and Foxa soon begin their own investigation of sorts, eventually finding the murder weapon and, along with it, more clues planted by the killer. Meanwhile, Fonseca seemingly gets hit with a rock while outside, and when discovered by Benjamin and Foxa, and brought back to the hotel, he stumbles upon a third body, this time that of Mr. Klemmer. Just when the terror seems to be at its peak, Benjamin makes a series of discoveries, including the fact that Klemmer was a former SS soldier and that certain rebels were after him for vengeance. However, with the radios getting fixed and the police arriving to take the case over, Benjamin’s shot at being a successful detective seems lost, until the answer reveals itself at last.

The Final Problem Ending: Who Killed Elisa and the Others?

The ending of ‘The Final Problem’ reveals the killer to be none other than Adela Figueroa, whose real identity is actually Elisa Mander. In fact, Adela is the name of the dead woman who hired Elisa as a maid, and later made her swap identities. This gave way to a symbiotic relationship, allowing the real Adela to lead a sexually liberated life, free from prying eyes, and simultaneously giving the fake Adela a chance to live in luxury. However, somewhere along the line, this engagement began to eat away at her subconscious. The real Adela seems to fetishize the life of commoners, in that she ditches the pompous nature of the elites in favor of simplicity, while still treating her wealth as a security net. All of this appears to be a fun exercise for her, and in Elisa’s mind, it’s a betrayal of all the suffering she has endured.

Thus, one day, Elisa decides to secure the identity of Adela for herself once and for all, and the way to do that is by faking a perfect suicide. The missing scarf that is brought up early on in the story plays an important role in all of this, as it allows her to slide a chair towards the door and snap it shut from the inside, thus completing the illusion. Where she slips up, however, is letting the real Adela eat strawberry desserts. Benjamin eventually discovers that the real Elisa Mander is recorded to be allergic to strawberries, and it is this inconsistency that creates doubt in his mind, doubt that ultimately leads him to the killer. The detail that fully solves the mystery, however, isn’t related to the real Adela at all.

Apart from becoming the one and only Adela, Elisa has a greater reason to embark on this island vacation, and it is to kill Mr. Klemmer, a former SS soldier responsible for killing Elisa’s husband during World War II. Though Klemmer managed to later pin the entire blame on his superiors and escaped justice to lead a wealthy life, he was eventually discovered by revolutionary forces, and from there, the information finally reached Elisa. Her trip to Santa Agueda, then, is intended to be a plan that kills two birds with one stone. With this, Elisa eliminates two of the people who have damaged her life the most, but in attempting to do so, she embarks on a self-destructive journey that ends with Benjamin uncovering the truth.

How Did Elisa Kill Dr. Seruya? Why?

While Elisa, as Adela, steps onto the island already prepared to kill the real Adela and Klemmer, the death of Dr. Seruya stands out as an odd addition to the plot. In fact, it’s not even explicitly confirmed whether Elisa really killed the doctor, or if it is a completely different part of the mystery that was never solved. However, all the clues point to Elisa as the killer, and from there, we can trace the steps back to arrive at a plausible explanation. The first thing to consider is the fact that Dr. Seruya was about to tell Benjamin something before Adela appeared at the spot and interrupted the meeting. While this may have been a coincidence, Elisa nonetheless figured out Seruya’s plan and decided to kill him right then and there.

The plot beat about Seruya and the bag of money is likely a red herring with regard to his murder mystery, as it’s more likely that he was meeting Benjamin to disclose his theories about Elisa’s death. However, from here, the details steadily get more obscure, as there’s no streamlined explanation for how she might have killed the man in a matter of minutes. There’s the fact that his door was locked from the inside, and the only explanation in this case seems to be that Elisa set up a ladder by Seruya’s window, then walked into his room normally, killed him, staged his body, and then fled the scene using the windows. That way, not only is the murder made much harder to solve, but the dramatic flair further takes the suspicion off Elisa.

Why Did Elisa Target Benjamin? Who Really is She?

It is one thing for Elisa to take the lives of Elisa, Dr. Seruya, and eventually Klemmer, but there seems to be a separate battle unfolding entirely on a psychological level between Elisa and Benjamin. Where the real Adela’s murder is designed to look like a suicide, Elisa soon gives up the ploy when she kills her next two targets. Instead, she takes on a distinctly more creative flair, akin to a ‘Sherlock Holmes’ novel, where evidence is carefully placed for the keen eye to see. In many ways, this serves as a meta-commentary on detective fictions of the kind, be it in the form of novels or their film adaptations, which used to be Benjamin’s bread and butter at one point. The real reason she toys with Benjamin, as it turns out, is that the two of them were once in a relationship that ended terribly.

The fact that Benjamin doesn’t even remember her face, despite his supposed observation skills, is a part of the point Elisa seems to be making with her dramatic presentations, as at the end she recalls the entire ordeal just for Benjamin’s sake. More than a decade ago, when Benjamin was still regarded as a superstar for his portrayal of Sherlock Holmes, Elisa was an aspiring actress who fell in love with him. As the two entered a sexual relationship, Benjamin made false promises about launching her career, only to move on and forcibly cease all communication with her not long thereafter.

It isn’t exactly a desire for vengeance that drives Elisa to go against Benjamin, but rather a desire to make him confront his own shortcomings. The story makes multiple references to how Benjamin once lost himself to pride and indulgence, and Elisa’s chance return in his life forces him to look into the mirror of his past. It also adds a new layer to her past comments about how Benjamin already, subconsciously knows who the killer is, but has been trying to block it with meaningless investigations. Where we are led to believe that the killer is Francisco Foxa, in reality, it is Elisa, a person Benjamin knew years ago, but never truly acknowledged.

Why Does Benjamin Let Elisa Go?

Curiously enough, Benjamin decides to let Elisa walk free despite figuring out that she’s the killer. The reason for this is tied to their own complicated past and how deeply Benjamin regrets wronging Elisa years ago. In a way, he understands that this entire path of near-endless suffering that Elisa had to set out on during World War II is ultimately his fault, and his final act in the series seems to be a way of making amends. By saving her life, he not only allows for a former SS soldier to get a taste of justice, but also gives Elisa a chance at completely reshaping her life. As Adela, she has access to untold amounts of wealth and luxury, which gives her, at last, the life that was once stolen from her.

There is also a reference to ‘Sherlock Holmes’ hidden in how Elisa’s story concludes. In the final moments of the series, we hear a voice-over narrating the opening lines of ‘A Scandal in Bohemia,’ the classic novel known for introducing the character of Irene Adler. Across all ‘Sherlock Holmes’ stories, she is known to be perhaps the only character to truly outsmart him, and the same holds true in the case of Benjamin and Elisa. That’s not all, though, as Irene turns into Holmes’ secret obsession of sorts, which also lines up with the ambiguous dynamic that their counterparts in ‘The Final Problem’ share. In their last interaction, the two determine that words are not necessary to express their feelings, and in effect, it turns the three murders into their own little secret.