Roger and Lauren are part of a team of detectives who have already uncovered a lot of complex and complicated cases. The other day they received one more, and this time the investigation will obviously drag on. The culprit left no trace, an almost perfect crime. But the team of professionals is not going to retreat, they intend to check all the strings, and so far there are very few of them. The crime scene has already been examined by experts, but the detectives want to examine it again and invite you to Invisible Killer as an assistant consultant. A pair of extra eyes will never hurt and you will probably find something, and detectives will pull the string and untwist the ball.