De veertienjarige Marco, een Roma-jongen, wordt aan de Deense grens aangehouden met het paspoort van een vermiste ambtenaar op zak. Inspecteur Carl Mørck en het team van afdeling Q onderzoeken het verband. De oorspronkelijke eigenaar van het paspoort blijkt kort voor hij verdween verdacht te zijn geweest van pedofilie en de zaak was opvallend vlug gesloten. Intussen weigert de stille, getraumatiseerde Marco met de agenten te praten. Hij slaat op de vlucht voor degenen die vinden dat hij te veel weet.
Nee, helaas is Het Marco-effect nog niet beschikbaar op Netflix in Nederland.
| Production | Henrik Zein | Executive Producer |
| Camera | Aske Foss | Director of Photography |
| Costume & Make-Up | Tina Norup Helmark | Makeup Designer |
| Editing | Per Sandholt | Editor |
| Production | Peter Nadermann | Co-Producer |
| Editing | Mette Lybæk | Editor |
| Art | Gitte Malling | Production Design |
| Writing | Martin Zandvliet | Co-Writer |
| Writing | Thomas Porsager | Co-Writer |
| Editing | Per K. Kirkegaard | Editor |
| Sound | Lars Ginzel | Sound Designer |
| Production | Wolfgang Feindt | Co-Producer |
| Production | Lina Wichmann | Post Producer |
| Costume & Make-Up | Susie Bjørnvad | Costume Designer |
| Production | Arwa Salmanova | Casting |
| Lighting | Andreas Kragh-Jacobsen | Gaffer |
| Crew | Jacob Sebastian Malm Carlsen | Stunt Coordinator |
| Crew | Hummer Højmark | Special Effects Coordinator |
| Sound | Sune Martin | Music |
| Sound | Nino Jacobsen | Sound Editor |
| Production | Tanja Grunwald | Casting |
| Sound | Markus Stemler | Sound Editor |
| Production | Doris Schrenner | Co-Producer |
| Sound | Frank Kruse | Sound Editor |
| Visual Effects | Martin Madsen | VFX Supervisor |
| Sound | Benjamin Hörbe | Sound Editor |
| Sound | Julien Naudin | Foley Artist |
| Production | Sandra Foss | Line Producer |
| Directing | Martin Zandvliet | Director |
| Production | Mikael Chr. Rieks | Producer |
| Writing | Anders Frithiof August | Writer |
| Writing | Jussi Adler-Olsen | Novel |
| Writing | Jussi Adler-Olsen | Writer |
| Writing | Jussi Adler-Olsen | Author |
| Camera | Martin Maryška | Focus Puller |
| Lighting | Daniel Kvarda | Gaffer |
| Costume & Make-Up | Charlotte Moe | Costumer |
| Sound | Sune Martin | Original Music Composer |
| Sound | Martin Saabye Andersen | Sound |
| Production | Greta Varts | Production Executive |
| Directing | Christian Bonke | Assistant Director |
| Writing | Denisa Marešová | Script Editor |
| Writing | Ditte Sun | Script Editor |
| Directing | Jette Keedus | First Assistant Director |
| Directing | Jude Kimuli | Third Assistant Director |
| Production | Malou Wiesneck | Production Manager |
| Production | Søren Frimodt-Møller | Production Manager |
| Production | Mascha Ott | Production Coordinator |
| Production | Fie Gehrs Madsen | Production Coordinator |
| Production | Nawa Al-ani | Producer's Assistant |
| Writing | Anders Thomas Jensen | Script Consultant |
| Production | Kristina Kornum | Line Producer |
| Production | Christina Pind Rasmussen | Production Manager |
| Camera | Mikkel Find | "A" Camera Operator |
| Camera | Johannes Sprogøe Fletting | "B" Camera Operator |
| Camera | Asker Frølund Andersen | Assistant Camera |
| Camera | Mikael Kort Kristensen | Grip |
| Camera | Philip Cooke | Assistant Grip |
| Camera | Kristian Appel | Steadicam Operator |
| Camera | Franz Borde | Focus Puller |
| Camera | Franz Borde | Steadicam Operator |
| Camera | Martin Samsøe | Focus Puller |
| Camera | Martin Samsøe | Steadicam Operator |
| Camera | Rune Johansen | Drone Cinematographer |
| Camera | Alex Suhr | Drone Cinematographer |
| Camera | Klara Crvckova | Still Photographer |
| Sound | Lars Gerrild | Boom Operator |
| Costume & Make-Up | Emilia Imperatore Bjørnvad | Costume Assistant |
| Costume & Make-Up | Sascha Valbjørn | Costume Assistant |
| Costume & Make-Up | Charlotte Hertz | Makeup Artist |
| Costume & Make-Up | Josefine Ranch | Makeup Artist |
| Production | Pavel Muller | Producer |
| Production | Veronika Skorepova | Line Producer |
| Production | Madara Kalnina | Production Manager |
| Visual Effects | Katharina Bormann | Visual Effects Coordinator |
| Sound | Martin Hedegaard | Original Music Composer |
