Once upon a time, abbess Maria and sisters Arsinoe, Ourania, Agathoniki and Chrysovalanto lived calmly and peacefully in the monastery of Agia Theodouli. Until they discover a man's corpse in the sacristy and their lives turn into hell... The investigation of the case is undertaken by the experienced police officer, Miltiadis Sofianos, and his rookie assistant, Hector Tsakalakis, with orders to conduct the investigation in strict secrecy. Sofianos and Tsakalakis have the nuns as prime suspects and interrogate them. Strangely enough, none knew the victim and none saw anything suspicious on the night of the murder. However, evidence soon comes to light that indicates the opposite: one of the nuns secretly put the victim in the convent and then murdered him.

The arrest of the abbess causes fear and disturbance to the rest of the nuns, who begin to doubt her innocence. The police pressure the abbess to admit her guilt, but she denies any involvement in the murder. Fearing possible condemnation, she decides to take fate into her own hands and begins a secret investigation with the aim of solving the murder herself. At the same time, Karaiskos and Stamatis also start an investigation to find out what happened to Petros. Meanwhile, Sofianos and Tsakalakis discover a new clue that proves that one of the nuns gave a false testimony. On the night of the murder, she left her cell and had a suspicious date outside the monastery.

The discovery of the theft of the painting further complicates the investigation of the abbess who is asked to solve this case in addition to the murder. At the same time, Father Fanourios suspects that something serious has happened in the monastery and decides to follow the movements of the nuns to find out. Sofianos and Tsakalakis examine the closed-circuit video of the morgue and approach the tracks of Karaiskos and Stamatis, while the abbess manages to find out the address of the victim's apartment. There, an unpleasant surprise awaits her that will endanger her life.

The consecutive absences of the Abbess from the monastery raise suspicions against Sister Arsinoe. The Abbess is forced to reveal her secret investigation and takes her along on the next mission. Sofianos and Tsakalakis use the findings from the forensic report and find out important information about Angelos' life. At the same time, Stamatis is afraid that the police will track them down and pressures Karaiskos to stop dealing with Petros' murder. A while later, one of the nuns is getting attacked inside the monastery.

The attack on the abbess leads Sister Arsinoe to the conclusion that the perpetrator of the monastery's crimes is among the nuns. Meanwhile, Karaiskos and Stamatis visit Agia Theodouli monastery trying to find clues that will lead them to the nun who has the solution to the mystery. At the same time, Sofianos and Tsakalakis come upon to a new revelation that overturns the facts so far: one of the nuns of Agia Theodouli has once been accused of murder...

Sofianos and Tsakalakis find out that Angelou had friendly relations with Karaiskos and decide to approach him. At the same time, the sisters Ourania, Agathoniki and Chrysovalanto receive threatening messages that upset them. In their secret investigation, Abbess and Arsinoe visit Doxa Byzantium, the team Angelou used to play football for, and find an important clue that lead them to their next mission. That same night one of the nuns will bring great disruption to the lives of the rest of the nuns.

After the explosion in the monastery of Agia Theodouli, nothing is the same. The nuns were saved, but Abbess and Sister Arsinoe are sure that they are now a target and the question is one, should they stop the investigations? At the same time, the police report speaks of an improvised bomb and the feud between Sofianos and Mytakos grows: are the nuns victims or perpetrators after all? Until the questions are answered, the sisters are taken to their new home, isolated and protected. However, they will not spend the first night alone. They will be somewhere very special, in the company of everyone involved in the story.

Abbess and Sister Arsinoe spend the night at the Pink Banana club and get involved in embarrassing situations. In their attempt to find information about Angelou, they come face to face with the police and Karaiskos, who is getting closer and closer to them. An unexpected meeting from the abbess's past will put her in a difficult position, while a little later Karaiskos and Stamatis approach the nursing home where the nuns are staying with dark intentions...

A few hours before the abduction, everyone's investigations are progressing closer and closer to their goal. The Abbess and Sister Arsinoe, knowing the details of Karaiskos' company, make a raid with unexpected results. Behind them is Sister Chrysovalanto, ready to discover that the nuns are lying once more. Katapodas, Karaiskos and Stamatis always in wild moods. Sofianos and Tsakalakis get, from an unlikely informant, information about the icon of Agia Theodouli, while Father Fanourios learns that Petros was a football player and is on the field. But the day will end unexpectedly for everyone...

A threat from the past terrifies Abbess Maria, causing her to flee into the night and disappear. Sister Arsinoe is in despair, as -on the one hand- she searches in vain for the abbess and on the other she is called to save Chrysovalanto from Karaiskos who has kidnapped her. Sofianos and Tsakalakis are informed by Father Fanourios about the mysterious relationship that a certain nun had with Petros Angelou, and they too look for the abbess for answers. Dimitris Kalogirou is also following in the footsteps of the abbess, trying to kill her...

The nuns have now learned that Abbess Maria is dead. They mourn her loss full of questions. Sister Arsinoe decides to tell the other nuns everything about the secret investigations of the abbess that led to her death. Sofianos and Tsakalakis try to "unmask" Dimitris, who is behind the murder, while Karaiskos seems to have escaped them. As the nuns and Father Fanourios mourn the loss of the abbess, one of the nuns, affected by the tragic outcome, visits the police station and confesses to the murder of Petros Angelos. Who is she?