I'm struggling to keep up with the subtitles (during the French scenes) but otherwise it's okay. Not sure if I'm watching it because it's a good (but slow) story or if I just want to know who the killer is.
The Tunnel is set against the backdrop of Europe in crisis. When a prominent French politician is found dead on the border between the UK and France, detectives Karl Roebuck (Stephen Dillane) and Elise Wassermann (Clémence Poésy) are sent to investigate on behalf of their respective countries. The case takes a surreal turn when a shocking discovery is made at the crime scene, forcing the French and British police into an uneasy partnership. As the serial killer uses ever more elaborate and ingenious methods to highlight the moral bankruptcy of modern society, Karl and Elise are drawn deeper into his increasingly personal agenda.