STORY LINE (in english):

'Due to the information from the business owner Pallenburg,  Essen police commissioner Heinz Haferkamp arrest a serial burglar named Brossberg.  Fighting the police in a firefight, Brossberg's brother is killed.  At the end of the court hearing, Brossberg swears revenge on the inspector and Brossberg's lover Frau Pallenburg.  Haferkamp doesn't really care because he believes that after a long prison sentence, no one will think of retribution.

When Brossberg was released eight years later, Mrs. Pallenburg stood in front of Haferkamp's door and claimed that she was afraid of Brossberg because she said he had allegedly wanted to come to her apartment.  Mrs. Pallenburg says that she wants to stay with Haferkamp for the time being.  Haferkamp is not very enthusiastic about this and tries to remove her from his apartment with the help of the patrol police.  When Mrs. Pallenburg threatens to commit suicide, he reluctantly accommodates her in his apartment, although he cannot take any concrete measures and has nothing against Brossberg.  Brossberg, in turn, is shadowed by Kreutzer on his own, but seems to lead an inconspicuous existence, so that initially nothing reminds of the vows of vengeance expressed eight years ago.

The story takes a turn when a shot is fired near the window, from a building being remodeled opposite from Haferkamp's apartment when he was at the police station and away from Mrs. Pallenburg, there.  The Essen police look at the bullet's ballistics

The police eventually find and chase Brossberg off of a construction site, across a river and onto a train where he is able to get off and hide under the railroad tracks.  Then, Haferkamp himself finds Brossberg and chases him into a foundary around molten metal and into the noxious upper areas of the factory. While chasing him through the factory, both suffer from carbon monoxide poisoning.  Haferkamp even passes out in sight of Brossberg, who - instead of killing him - just walks past him.  Both are later found hospitalized.  Now Haferkamp - through tips from his ex-wife Ingrid - doubts the suspicious actions of Mrs. Pallenburg.  

It turns out that she has the Haferkamp apartment wiretapped with the help of a bug' that Haferkamp himself found.   Mrs. Pallenburg is caught staging the attempted murder herself and she' may really 'have wanted to eliminate Haferkamp now also together with Brossberg, who had since been released from custody.  

Commissar Haferkamp had suspected a voluntary romantic relationshio of some kind between Mrs. Pallenburg and Brossberg.  The police had many pictures falsely constructed and arranged showing Brossberg very close with another woman, them together even carrying out a money transfer at a bank, together.  Mrs. Pallenburg seeing these two together and being told about their bank issue - all previously unknown to her - by Haferkamp would have created enough jealousy to turn Mrs. Pallenburg against Brossberg, but maybe it doesn't work.

In his apartment on a later night, police commissioner Haferkamp looks at his drink as he returns from another room.  He 'apparently lets himself be anesthetized with a sleeping' pill administered to him in 'his drink by Mrs. Pallenburg and puts theirs lives in danger when Mrs. Pallenburg manipulates the heater and gas flows into the living room with the now sleeping Haferkamp.'  The lit candles suddenly go out.  She turns the light switch on and off two or three times.  

However, since Haferkamp had only 'apparently drunk a small bit of the' suspicious drink with 'the sleeping' pill and poured out the rest of the drink onto the carpet when she wasn't looking, he' was able to stay awake, only pretending to be unconscious. She walked around after 'the toxic fumes were turned on by her.  After, he pretended to be knocked-out, he gets up and confronts her.  'She runs and tries to escape and he catches her at the door and handcuffs Mrs. Pallenburg closing the door to the apartment, afterward. 

'Brossberg is then' found outside, spot-lighted and 'arrested' just steps away from Haferkamp's place by the other police the minute after Haferkamp whistles out of the window at them.  The police were there the whole time. '

SOURCE: (updated)
from Wikipedia Germany, Wikipedia the free encyclopedia
-- https://de.zxc.wiki/wiki/Tatort_(Fernsehreihe)#Liste_der_Tatort-Folgen
(see: 'Main article : List of crime scene episodes')