Nina Wenzel used to be an undercover agent. After her sister's death five years ago Nina gets child custody of the three orphans and quits her dangerous job. In her new family-life she manages to retain some of her skills. When Wolf Geiger, the last person Nina imprisoned, escapes, Nina's old skills are needed again.

On the outside, Martin Dreyer looks like the nice neighbor next door. He lovingly looks after his paralyzed brother and his friends have never noticed him in a negative way. Nobody sees what a monster lies dormant inside him. No one suspects the incomprehensible. Martin suffers from a terrible burden: an obsessive desire for young girls. When Martin meets the young, petite Sonja one day and falls in love with her straight away, he believes in a new life. He asks her to marry him. She is surprised at his quick decision, but then agrees. What Martin doesn't know until then is that Sonja has a little daughter.

A love triangle forms between post-Enlightenment writer Friedrich Schiller and two sisters -- one who became his wife, and the other, his biographer.

Strange, rhymed advertisements in the TIMES unsettle three London gangsters - and rightly so, because soon the first of them are killed. The mysterious killer also catches a shady lawyer. Higgins and Lane find out that the key to the crimes is an unsolved diamond heist from jeweler Bolden. It looks like those involved are fighting over the loot. Eventually, it turns out that the "robbery" was actually a set-up insurance scam that Bolden was personally behind and that killed his employee. Shortly before the last survivor is sent to the afterlife, Higgins and Lane are able to confront the "invisible" murderer.

While searching for an ancient burial chamber in Cologne, Dr. Bea Valori has suppressed the fact that she is a very lonely romantic at heart. This seems to change when colleague Michael Burger introduces her to the charismatic Jürgen Wiedener. He teaches minnesong at the university and has very specific ideas about a life for two. At first, Bea feels flattered by Jürgen's declarations of love. But then his courtship becomes more and more insistent. He is prepared to give everything for Bea. Even if it costs him his life...

A sound designer hears a child scream in pain while recording in the forest.

The scientist Agnes must take care of a foreign flat. Without her family knowing about it, she visits this flat regularly and begins a parallel life. One day she falls asleep there. When she wakes, a foreign man lies beside her in the bed.