A female local politician has been murdered in the Thai boxing club. When Dan and Flemming arrive at the scene, they discover that the blood from the deceased forms a pattern of a butterfly, resembling the club logo. The first to be interrogated in the case are the deceased's group of friends, who train in the same club. And they are not afraid to lie to each other nor to the police.

Roland has previously lied about his alibi, so can he be trusted when he claims that Rikke had the murder weapon on her when she met her killer? Roland is not the only one in the friend group with a motive, so Dan and co. must follow every lead, and with Benjamin on paternity leave, the others must run faster.