The investigation brings to light the dark side of Fran’s life: he had established contact with some mysterious person in Holland, and he had an affair with an unknown lover. Did Fran die because he was involved in some shady business? Or was it a crime of passion? Both Candela and Díaz make progress in their respective investigations, carried out independently. Díaz believes Fran used his contacts from the milieu of a dangerous drug smuggler. And Candela makes an uncomfortable discovery – Fran’s mysterious lover is someone very close to her.
Reyes hasn’t been found, but the search operation leads to tracing down a sunk boat which will provide new clues. The boat was used for smuggling African diamonds, and was found by Fran in a diving excursion. Diamonds are the shady business he was involved in. Candela cannot accept defeat in the search for Reyes, or the slowing down in the speed of the investigation as a result of the Descent, a religious festivity that paralyzes the island every four years. Desperate, she tries to get Díaz’s cooperation, who is also vent on finding the real culprit. The murderer feels the investigation is closing down on him. He considers fleeing, but he hasn’t found the diamonds hidden by Fran yet. And he diverts attention to everyone’s ideal false culprit – Díaz.
The murderer, upon being found out, kills Reyes. From that moment on, he faces the difficulty of getting rid of the body in an island like El Hierro, where it is difficult to vanish without trace. Especially after the disappearance of the local police officer gives rise to a public outcry. There is a reaction in the island. Police forces, civil defense services and volunteers start a desperate search. The most likely scenario is that the murderer Reyes was investigating is back in action. Candela is devastated; she feels guilty because she is the one who enlisted Reyes for an investigation that strictly speaking was not part of her work duties.
Díaz avoids being arrested by desperately fleeing. But leaving the island without being found out is impossible, especially with a police operation that shut up firmly the few available exit routes from the island. Finally, Díaz gets caught. And the island sighs, relieved – they will be able to celebrate their Descent in peace. Only three people in the island seem anxious: Díaz himself, who knows that someone has planted false evidence to frame him; Candela, who has a hunch there must be something wrong; and the murderer, who got the police off his back, but who continues looking for the diamonds that are at the root of his whole adventure. In the middle of the Descent festivities, the murderer discovers the location of the diamonds.
The murderer, taking advantage of the chaotic situation during the Descent, manages to get hold of the diamonds. But now he must face a new obstacle – the drug smuggler whose help Fran had enlisted has been following him, and he wants to take the diamonds himself. Meanwhile, Candela and Díaz go over their investigations together, and find the key to identify the murderer. They trace him down when he is on his way out of the island. They have caught him. But he is not prepared to surrender.
Nancy writes a gossip column and gets a little fancy with the facts.
Kirkman mobilizes a frantic hunt for the bioterrorist. Lorraine plays hardball and pushes the opioid epidemic into the campaign fray.
Trailing in the polls, Kirkman weighs forcing the FBI's hand over the bioterrorism plot. Emily struggles with her mother's final wishes.
A stray Russian bomber jeopardizes Seattle, Mars crusades against a drug company, and an event from Aaron's childhood vexes Kirkman's campaign.
Emotions run high after despicable fake news goes viral, Isabel makes waves with a controversial appeal, and Wells finds a clue pointing to conspiracy.
A heated debate over child marriage roils Kirkman's staff. Opioid addiction hits home for Mars. A biohacker turns Wells onto a chilling new threat.
Aaron's heritage and a widespread teachers' strike become polarizing issues, and Wells discovers a sinister pattern in a flu outbreak.
A political attack on Kirkman puts privacy and transgender rights in the spotlight. Aaron weighs a major decision. Wells and Eli track a bioterrorist.
A dying Guatemalan child in a Texas hospital brings immigration to the fore. A mugging opens Kirkman's eyes to the realities of life in the capital.
Satellite images have revealed a giant face that appears to be carved into the Earth in Alberta, Canada, which has now become known far and wide as "The Badlands Guardian."
Among the guests on Graham’s sofa tonight: everyone’s favourite hot vicar, Fleabag's Andrew Scott, now starring in Black Mirror; and singer Paloma Faith, now turned actor to play the villain in Batman TV prequel Pennyworth.
Now running for office for the first time, Kirkman and his nascent campaign stumble out of the gate. Wells gets a critical reassignment.
On election day, Kirkman turns to his therapist to assuage his conscience about the events -- and his own decisions -- of the momentous prior 36 hours.