A show about a group of criminals robbing some of the biggest financial institutions in Spain is going to have some casualties. But it’s always devastating when a beloved character from a show with a cult following is killed. And while plenty of viewers were devastated by the fate of one of Money Heist's, Nairobi (played by Alba Flores), her co-stars were even more upset. 

Introduced as "a hardened optimist" who's "crazy but a lot of fun," Nairobi was a teenage counterfeiter before her foray into the world of drugs. As the heist group begins their mission to print more than 2 billion euros (about $2.3 billion) of unmarked, untraceable bills, she's the quality control manager in charge of the printing operation. While a vital part of the crew, she doesn't get any more backstory until the fifth episode, when we learn that she lost custody of her 7-year-old son and desperately wants him back.

Once we discover more about Nairobi’s motivation to join the team, she quickly becomes a fan-favorite character, delivering well-placed punchlines, solid emotional support and encouraging progress updates as the heist continues. Over time, Nairobi becomes the heart of the series, bonding with fellow singleton Helsinki and building a very real — if unconventional — family unit among the group. 

But Nairobi's dreams to expand her family and make money to provide for her son are cut off in Part 4 when she's brutally murdered by sadistic security guard Gandía (José Manuel Poga). It was shocking both to fans and stars of the series alike — "I don’t get it either," star Úrsula Corberó (Tokyo) said in a press conference ahead of Part 5. "There were a few friends I had there, and they killed the best one."

But executive producer and director Jesús Colmenar said that Nairobi wouldn't have lasted long as the gang faced their toughest obstacles in Part 5. "Nairobi’s personality was not cut [out] for the war we find in this final season, so she wasn’t supposed to be here. She wasn’t cut [out] for that," he told reporters. "And I think that this adds momentum to our characters that would be complex to add otherwise. We kill our characters, and I think it adds tension, and it’s a good thing not to be able to know who will be killed and what will happen."

After wrapping her last scene, Flores tearfully told the crew with whom she'd worked closely over the past four years, "I want to thank you all for everything you've taught me. I've grown here as an actress more than I ever imagined I would, and as a person, too."

The emotional speech is captured in the documentary Money Heist: The Phenomenon, which is streaming on Netflix. After wrapping on the series, Flores says that she's ready for her next challenge: "It's over, and I have nothing on the horizon," she explained. "It's a really liberating feeling because, well, I need a rest." (And so do the rest of us after re-living such a brutal moment.)