STORY LINE (in english):
Police senior commissioner 'Konrad, who has just returned from vacation learns that he is getting a nice welcome back home at his homicide desk in Frankfurt.  He hears from the' administration 'of the Butzbach prison that an Austrian inmate named Franz Jaczek will be released early.  Franz was responsible for an attack on an armored car, in which 900,000 Deutschmarks were captured.  

The robbers involved ruthlessly shot the two drivers.  Later after the murder, Franz blamed his accomplice who himself, 'was also killed in the exchange of' gunfire and his claim could never be disproven.  So, Franz 'was only convicted of robbery.  'Konrad suspects that Franz will soon' be a bother to 'him, again.

In fact, Franz Jaczek is up to something again: he plans to kidnap the wife of the banker Kurt Quaas, for whom Franz currently works as a gardener, and then to extort a large sum for' her ransom and definitely to 'bother' Konrad, again.  

Franz Jaczek now a free man after all these years, seeks out his Bavarian former partner in crime 'Ferdi Kofler; Franz and his accomplice went into hiding with him at the time.  

They play with open cards: Konrad' is supposed to 'know that he is dealing with the cold-blooded Franz, but Franz himself should' have someone along with him that is a lot like him (doubled) 'by Ferdi Kofler.  Since' Ferdi may have chatted too much about these kidnapping and extortion plans in front of his girlfriend Irmi, 'she is also forced to be 'brought on board and is supposed to play' like she is 'another hostage.

They decide to go through with the kidnapping and Franz even brings in a third man a Berliner: Willi Mattfeld, who was hired specifically for the purpose of the kidnapping.  'Martina Quaas, Kurt's wife is' abducted by them and 'Franz calls the banker Kurt her husband and in his instructions he asks for two million Deutschmarks, gives his name and also mentions commissioner Konrad.  He also claims to have a second hostage (whose identity he does not reveal) under his control.  For the handover' of the money, 'the police'' are to 'block a main bridge in the middle of Frankfurt's city center to any traffic during rush hour.  The kidnappers' car would be the only one to remain on the bridge, and Franz says that police senior commissioner Konrad should hand over the money, personally - otherwise Franz threatens to murder the hostages.

After a detailed discussion within the crisis team that has been convened, 'it is decided to deal with Franz's demands first.  After Ferdi and Willi' drive onto 'the middle of that bridge in a stolen security van, the Frankfurt authorities assemble an enormous force that locks and secures the bridge on land and' in 'the water.'  

Commissioner Konrad 'and the hostage takers come into' direct 'contact and they present the now-hooded Irmi, actually Ferdi's girl friend, as Martina Quaas, which is immediately noticeable.'  Franz and the kidnappers may not know this.  Konrad also says that he actually wants to speak to Franz, whose attempt of an 'imitation' by Kofler is not 'successful to him. 'The situation almost escalated when a' civilian 'sports boat broke through the barriers that had been set up in the waters around the area.'  

Eventually, Konrad and the cops 'decide to hand over the ransom.  The perpetrators' apparently manage to escape in the traffic that had been restored again, but without having released the banker's wife Martina Quaas, the hostage.

Later, Franz personally intercepts commissioner Konrad right 'in front of his house and nonchalantly claims that he has nothing to do with the matter.  He only accuses Willi Mattfeld and Ferdi Kofler of the act and Franz goes on about describing them as extremely brutal and advises Konrad and his forces, again to kill them first in any rescue' attempt 'before they kill the hostages. For their names and whereabouts,' Franz actually 'demands another million.  Senior commissioner 'Konrad sees through Franz's double game, but has no way' to act against him then and there, at least.

'The crisis team refuses to provide a further million ransom, but Quaas steps in with his private fortune.  In the midst of the hustle and bustle of pedestrians at the Frankfurt Hauptwache location, Konrad hands over the ransom called “the lilac” then Franz moves away from this location, but there is a tracking device installed in the suitcase full of money. 

So, the chase begins and Franz nevertheless' temporarily 'escapes.

In return, 'Franz told the police the whereabouts of the rest of the kidnappers.' They are holed up in the rubble of fortress ruins 'in southern Bliesgau and' they 'want to move to France.  

Police senior commissioner Schäfermann is asked for assistance.  

Meanwhile, tensions are arising between Willi and Ferdi.  

Just as Willi wants to get rid of Ferdi and Irmi, the two are eventually surprised and arrested by the police at the fortress.  Irmi is also arrested and the banker Kurt Quaas' wife Martina is able to be freed unharmed.

Now at the same time, Franz is on his own.  He' sneaks into the Quaas' residence, 'overpowers the' authorities 'there and forces the banker, who is not yet aware of the successful liberation of his wife, to fly him out of there in the banker's business plane; Franz takes Kurt Quaas' little son Sigi as hostage.  But, the' attempt 'fails partly because Kurt Quass left the' flight filing paperwork and 'approach map for the airport on his desk.  

Since, there was no reaction from Quaas' house, Konrad' takes this as a warning of more trouble.  He goes there and 'finds the notice there and has the airfield surrounded by massive police forces.' Franz is caught and surrenders.

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 written by Jürgen Scheschkewitz and Stefan Murr