Spoiler warning: This guide covers the full ending of Netflix’s The Final Problem (El problema final), including the Elisa/Adela identity twist, every murder motive, and why Basil lets the killer walk. Stop here if you have not finished Episode 4.
TL;DR
- The Final Problem is a 4-episode Spanish limited series (Netflix, September 25, 2026) adapting Arturo Pérez-Reverte’s El problema final, directed by Félix Viscarret, starring José Coronado as retired Sherlock Holmes actor Benjamin Basil.
- A 1959 storm traps 13 people at a Mallorca-coast hotel. The first death looks like English tourist Elisa Mander‘s suicide. It is staged murder. Dr. Seruya and Mr. Klemmer die next.
- Ending twist: the woman everyone knows as wealthy guest Adela Figueroa is actually Elisa Mander. The corpse in the locked pavilion was the real Adela.
- Elisa kills Adela to steal her life, kills Seruya to protect the disguise, and kills Klemmer for a World War II revenge tied to her late husband.
- Months later, Basil reconstructs the crime on a film set, proves the identity swap with RAF records and physical tells, then chooses not to turn Elisa in.
- Their goodbye mirrors Conan Doyle’s A Scandal in Bohemia: Basil is Holmes; Elisa is his Irene Adler. The official case stays unsolved.
- Chart heat (late Sep 2026): ScreenRant cites FlixPatrol placing the show around #4 worldwide TV, trending in 71 countries, as high as #1 in 8, and about #9 US TV.
- Season 2 is not announced. Netflix billed it as a completed limited series.
What is The Final Problem on Netflix?
The Final Problem (El problema final) is a Spanish-language period murder mystery built as a classic closed-circle puzzle. Netflix announced the premiere on its About Netflix press page: four episodes, September 25, 2026, adapted from Arturo Pérez-Reverte’s bestselling novel of the same name.
José Coronado (The Snow Girl, The Truthers) leads as Benjamin Basil, a fading screen star once famous for playing Sherlock Holmes. He is not a licensed detective. He is an actor who spent years performing deduction, then gets stuck inside a real crime that refuses to stay theatrical.
Director Félix Viscarret steers a Mod Producciones limited series written by Alberto Macías, Carlos Molinero, and Marisol Farré, with Fernando Bovaira producing. The show leans hard into locked-room logic, mid-century glamour, and Conan Doyle callbacks without pretending Basil is the literary Holmes.
If you came here after chart-chasing other Netflix mysteries, pair this with Bamfuzzle’s His and Hers Netflix ending explained and Archive 81 ending explained for more closed-door twist breakdowns.
Premise: 1959, Santa Agueda, and 13 suspects
Spring 1959. A violent storm cuts off a small island off the coast of Mallorca. Thirteen people are stranded at a secluded luxury hotel. Communications fail. Nobody can leave. Nobody new can arrive.
Then a quiet English tourist named Elisa Mander is found dead. The first read is suicide. Basil smells staging. Hotel manager Mrs. Ausländer wants composure. An aspiring thriller writer, Francisco Foxá, latches onto the case as both witness and would-be chronicler. Together with Basil, he starts treating the hotel like a stage set full of props that refuse to behave.
Netflix’s official synopsis frames the setup cleanly: every guest and staff member becomes a suspect in a crime more intricate than anyone expects. That is the surface pitch. The deeper pitch is identity, class resentment, wartime guilt, and an old personal betrayal that only becomes visible after the storm clears.
Cast guide: who plays whom
Use this as a quick map before the spoilers hit.
- José Coronado as Benjamin Basil, retired Sherlock Holmes actor turned reluctant investigator
- María Valverde as Adela Figueroa (the identity everyone sees; the twist makes this casting do double work)
- Martiño Rivas as Francisco Foxá, aspiring thriller writer and Basil’s literary-minded partner
- Maribel Verdú as Mrs. Raquel Ausländer, hotel manager under pressure to keep order
- Gonzalo de Castro as Fonseca, ambitious film director later tied to the movie recreation
- Cristina Kovani as a young, passionate actress in the ensemble
- José Condessa as Tony
- Pepón Nieto as Dr. Seruya, the doctor who notices the first death was tampered with
The ensemble also includes guests and staff who circulate as red herrings while the real game sits in plain sight. Coronado’s Basil is the show’s engine: vain, sharp, wounded, and better at noticing other people’s tells than his own.
SPOILERS: beat-by-beat ending explained
Everything below assumes you finished Episode 4.
The opening death is not who you think
For three episodes, the hotel treats the first corpse as Elisa Mander. Basil keeps circling the locked pavilion: orange shawl, chair jammed near the door, rope, missing sand, details that feel wrong one by one and devastating together.
The killer twist: the dead woman is the real Adela Figueroa. The living woman everyone calls Adela is actually Elisa Mander.
Elisa had worked as Adela’s assistant. The two women had already swapped identities before, letting wealthy Adela slip social rules while Elisa tasted privilege. Resentment hardened. When the island trip offered a chance to make the swap permanent, Elisa took it.
How Elisa staged the locked-room suicide
According to post-premiere explainers from India Times, Koimoi, FilmiFeed, and Auralcrave, the mechanics land like this:
- Elisa strikes the real Adela (temple blow with a stool in several reconstructions)
- She uses the pavilion/storeroom pulley and rope to hang the body and sell a suicide
- She places a chair on a shawl, locks the door, then pulls the shawl through the gap under the door from outside so the chair appears to have blocked the latch from inside
- The rope is weakened so the break and fall look accidental or suicidal rather than engineered
Basil misses the full picture on the island. Months later, while shooting a film recreation of the Santa Agueda case with Foxá writing and Fonseca producing, he rebuilds the room on a studio set and finally sees the trick as a piece of stagecraft he should have recognized sooner.
Why Dr. Seruya dies
Dr. Seruya examines the first body and notices the rope was tampered with. Instead of immediately protecting everyone with that information, he holds it for leverage. That makes him dangerous to Elisa’s stolen identity.
Killing Seruya is not the original plan. It is cleanup. If the doctor tells Basil the suicide is fake, the identity question collapses next. Seruya dies because silence is cheaper than exposure.
Why Mr. Klemmer dies
Klemmer is the revenge target that brought Elisa to Santa Agueda in the first place. Coverage consistently ties him to Elisa’s late husband John, a pilot shot down over Dresden, imprisoned, then executed after a failed escape. The execution order is linked to Hans Ludwig Klemmer. After the war he rebuilds a quiet civilian life. Elisa does not forgive that.
A Paris Match fragment and other planted reminders help Basil realize someone deliberately dragged Klemmer’s wartime past into the hotel. The German guest is not random collateral. He is the destination of a long plan, disguised under Adela’s name.
How Basil proves Adela is Elisa
Basil’s breakthrough is documentary and physical, not a last-second confession.
- He notices the surviving “Adela” has working hands closer to a typist than a lifelong heiress
- RAF records and Elisa’s old identification confirm what she looked like and who she was before the swap
- Allergy details (strawberries in several explainers) fail to match the corpse versus the survivor: the living woman avoids what RAF paperwork says Elisa cannot eat; the dead woman does not fit that profile
- Reconstructing the pavilion on the film set shows the locked-room was a performance, not an impossibility
Basil invites the woman still calling herself Adela to the set, then to dinner, and walks her through the solution. The case flips from “who killed Elisa?” to “who has been pretending Elisa was the victim all along?”
Why Elisa tries to kill Basil
Elisa and Basil share a buried history. Years earlier she was an aspiring actress. He encouraged her, promised access, then discarded her when it suited him. Contacts stopped answering. For him it was a footnote from a self-indulgent career peak. For her it was formative humiliation.
Finding him on the island turns the murders into a personal challenge. She wants the man who played Holmes to notice her design. When he gets too close, she leaves him with a car engine running in a garage, counting on fumes. Basil anticipates the move and escapes. Their final confrontation is less chase scene than reckoning.
Why Basil lets Elisa walk (and conviction status)
Basil has enough to destroy her. He does not call the police.
He knows she killed Adela, Seruya, and Klemmer, and that she tried to kill him. He still chooses silence. Explainers from India Times, Koimoi, and FilmiFeed land on the same motive: Basil accepts that his earlier cruelty helped shape the person standing in front of him. He does not absolve the murders. He owns his share of the origin story.
The deal is conditional. Elisa walks, but Basil keeps the evidence and the truth. If she kills again, he can still expose her. The Santa Agueda case therefore stays officially unsolved. The mystery is closed for Basil and open on paper.
Irene Adler parallel: In the closing beat they invoke A Scandal in Bohemia. Elisa addresses him as Mr. Holmes. He answers as Mrs. Adler. Basil even frames the island not as Moriarty at work, but as Irene Adler outplaying him. She is the woman who forced the actor-detective to see himself.
For another Netflix ending where identity and moral compromise collide, see Bamfuzzle’s School Spirits ending explained.
Chart heat: why the show is everywhere right now
Days after the September 25 drop, the series jumped from curiosity to chart animal. On September 28, 2026, ScreenRant reported FlixPatrol numbers that explain the Discover spike:
At the time of writing, The Final Problem is the 4th most-watched TV show on Netflix worldwide, according to data from FlixPatrol.
Key beats from that coverage:
- Debuted around #6 worldwide a day after release, then climbed to about #4
- Trending in 71 countries
- Ranked as high as #1 in eight of those markets
- Roughly #9 on the U.S. TV chart
- Global TV chart led by Monster: The Lizzie Borden Story; U.S. TV chart led by A Different World
That is why ending queries (“who is the killer,” “Elisa twist,” “does Basil let her go”) are moving now. People finish four episodes in a night, then need the identity swap spelled out. Bamfuzzle’s Monster Lizzie Borden Netflix number 1 despite bad reviews sits next to the same chart conversation if you are tracking what else is eating Top 10 slots.
Season 2 status: limited series, no renewal yet
As of late September 2026 coverage, Netflix has not announced Season 2.
FilmiFeed’s season 2 roundup stresses the important label: Netflix presents The Final Problem as a Limited Series, the same language used before premiere. Episode 4 is described as resolving the final problem. There is no official sequel novel queued as an easy Season 2 roadmap, and no public Netflix renewal notice.
Could Basil and Foxá carry another case? Narratively yes. Basil ends the story proven as a real investigator, and Foxá is already the Watson-shaped writer beside him. That is possibility, not a green light. Until Netflix or Pérez-Reverte announces another project, treat the show as a finished miniseries.
Book vs series: what changes
Pérez-Reverte’s 2023 novel El problema final is the source. The series follows the novel’s puzzle spine closely while shifting geography and some closing locations.
Auralcrave notes two clear adaptations:
- The novel places the island mystery on a small Greek island; the series moves it near Mallorca
- The book’s later reunion path includes Elisa’s villa on Lake Garda; the show centers the reveal around a film-set reconstruction and restaurant confrontation
The Conan Doyle homage stays intact either way. The novel title nods to Doyle’s 1893 Holmes story “The Final Problem,” while Basil’s surname and profession wink at Basil Rathbone, the classic screen Holmes. The series keeps that literary game, then lands the Irene Adler farewell as the emotional punchline.
FAQ
Is The Final Problem based on a true story?
No. It is fiction adapted from Arturo Pérez-Reverte’s novel, with heavy Sherlock Holmes literary references. For true-crime adjacent Netflix explainers in the same lane, Bamfuzzle’s Is The Woman in Cabin 10 based on a true story? covers how “inspired by” framing usually works.
Who is the killer in The Final Problem?
Elisa Mander, living under Adela Figueroa‘s identity after murdering the real Adela and staging the locked-room death.
Does Basil catch the killer?
He solves the case. He does not deliver a courtroom conviction. He withholds the truth from authorities after confronting Elisa.
Why does Basil let Elisa go?
Guilt over how he once used and abandoned her as a young actress, plus the Irene Adler-style recognition that she outplayed him. He keeps leverage if she kills again.
How many episodes are there?
Four. All dropped together on September 25, 2026.
Is there a Season 2?
Not announced as of late September 2026. Netflix bills it as a limited series with a resolved central mystery.
Where can I watch it?
On Netflix, in the original Spanish with available subtitles and dubs depending on territory.
What should I watch next?
If you want more twist-forward Netflix mystery explainers, start with His and Hers, Archive 81, and School Spirits.
