STORY LINE (in english):

'After a school fire, an initially unidentifiable corpse is found in the rubble. An autopsy reveals that the cause of death was a broken neck.  

A piece of jewelry in-tact was found there, after the fire.

According to investigating senior commissioner Veigl, there are several suspects who benefit from the fire in different ways. 

The teacher Dr. Hildegard Förster has been complaining about the ailing building for a long time and quickly ensures that the architect Ruby, who is her good friend, can present a plan for a new building to the building authority.  

The Riedel couple, who both lived as caretakers at the school and lived apart, were both not at home during the fire and can now collect a high sum insured. Enrico Riedel in particular is targeted by the investigators because he spends more money on his expensive hobbies like water skiing, than he apparently earns. 

After visiting their boat house rental property, Veigl and Brettschneider sit at a cafe, toast cheers and have a glass of beer and talk about the case..

Veigl's other assistant Lenz is spying on Enrico Riedel at the the boat house property on the water.  Lenz calls Veigl from a pay phone and they talk about how Enrico had other brushes with the law.

Veigl talks with his boss, director Härtinger about what insurance payoffs would benefit  Mr. Reidel.

After more spying on Enrico at the boat house waterfront property by Veigl's police assistant Lenz, Lenz goes to a pay phone and calls Veigl to say that, Enrico Riedel has separated from his former young friend named Babette Götz who suddenly leaves the property on the water and goes back to Munich after an argument. 

The two policemen go there to visit Ms. Götz.  She answers more of the police's questions. She asks for a cigarette after Veigl tells her that she and Enrico were not together on the night of the fire.  She revokes the alibi that she gave him at first. Veigl's police assistant Lenz finds out from her and other sources however, that Enrico Riedel needed the alibi to cover another crime: on the decisive night Riedel and an accomplice, a guy named Ludwig 'Lulle' Obermeier had robbed an American tourist named Harry Brooks that they drank beers with. They were dirt bike and off road jeep riding when it actually happened. They had met after boating and wind surfing that day. So, the fire focus turns away from Enrico Reidel.

Veigl finds out that Svetlana 'Sweetie' Ruby, the daughter of the architect Mr. Ruby who was traumatized by a previous experience, started the fire in order to get her father another job.  She knew that the caretakers were on vacation.  But, she did not know that the caretaker Ms. Riedel had allowed two young unknown women who dreamed of a career as a singer and musician to use the school as emergency quarters.  

The piece of jewelry was left behind by one of them, possibly a younger woman about 26, born in the month of June or July, foreign, without ID or any known family members, who was babysat by a now elderly lady in a wheelchair.  The elderly lady in the wheelchair is named Frau Roon who contacted Veigl's office and told Veigl's assistant this.  Ms. Roon later visits again, saying that the child's name is Barbara and there are her childhood photos.

Veigl goes back to the architect Mr. Ruby and asks him more questions.  Veigl finds Ms. Hildegard Förster living at his household.  In addition to Mr. Ruby's kid having been at the fire. The woman 'Barbara' and a woman named 'Stuki' may have been there when the fire happened, one of which is the girl now at the piano in the bar that they're asking questions at, possibly named 'Podium'.  They question the girl when she gets up from the piano, she confirms to the inspector that she and her friend were surprised by the fire, heavily drunk, and that they both tried to escape. Her friend 'Stuki' fell to her death while she escaped.  Because she felt very guilty, she did not report it to the police and even more evidence leads back to the Ruby household.

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')
-- Book by Erna Fentsch