This drama is based on the childhood memories of Hans Jürgen Massaquoi, who was one of the few black native Germans in Nazi Germany. In 1935 at the age of nine, he lives with his German mother in a small flat in Hamburg's working class district Barmbek, while his father and grandfather had left the country. Although the boy is not persecuted by the Nazis and dreams of joining the Hitler Youth, his skin color makes him a target for racist abuse...
There is good reason for Sir Douglas Wonderly to summon the family and a lawyer to his stately home. He wants to announce a change in his will. At the same time, a dangerous mental patient escapes from a nearby psychiatric ward. Higgins and Lane are put on his trail. But the arrest of the psychopath proves to be extremely difficult. Shortly thereafter, a mysterious hooded man is on the loose in the castle. He frightens Sir Wonderly so much that the old man suffers a shock and falls into a coma. But that's not all: the will suddenly disappears and two sons are murdered. Sir John personally intervenes to solve the case with Higgins and Lane.
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.
