All in the Family

SM09: All in the Family is a side mission in Deus Ex: Mankind Divided. It is available for Adam Jensen to complete during his second visit to Prague, assuming you completed SM04: The Calibrator by making a deal with Otar AND, during M7: The Rucker Extraction, you dealt with Louis Gallois by sparing or killing him.

Completing this mission will unlock the secret achievement/trophy of the same name.

Walkthrough
Upon returning to Prague, Otar will contact Jensen and ask him to visit Máša Kadlek, manager of the Red Queen. This will originally show up as a Point of Interest, One Last Favor, before you talk to and accept the mission from Máša.

Long story short, Máša wants her son, Dominik, to be married off to strengthen her connections but he wants to sit at the kingpin's table with Radich Nikoladze. As she cannot send any of her thugs into rival Dvali territory because of politics, she will task Jensen with abducting him without raising an alarm and gives him a photo to identify Dominik, who has a giant star tattoo below his left ear.

Infiltrate the Dvali Apartments
Dominik is staying at one of Radich's safehouses, Hotel Narikala, also known as the Dvali Apartments. The safest way to infiltrate the safehouse is though the alley behind the Irish Stool. Either hack the gate or jump over the adjoining wall, then climb the ladder and jump to the balcony on the left or use the scissor lift in the corner. The balcony will take you inside one of the apartment units.

Find the Control Room (optional)
Once inside the apartment building, make your way upstairs to apartment 95 and enter using the code 0666. A button on the TV stand will open a secret door on the opposite wall. Enter and you will see the security terminal. To shut off all the cameras and security panels, enter the password ST33LB3AM5.

Find and Incapacitate Dominik
Descend to the ground floor and deal with the thugs in the courtyard. Dominik will be found in the adjacent laundry room, talking on the phone with someone about Dvali politics. Knock him out however you see fit.

Store Dominik in the Locker
Drag Dominik up to apartment 86, preferably after having dealt with the two thugs inside, then bring him through the poker room and to the balcony. If you used the scissor lift to get up to the balcony, go ahead and put Dominik inside and use it take him down, otherwise you will have drop down and bring the lift up first to avoid Dominik falling to his death. Place him in the left storage unit, then close the unit's door to complete the mission and net the achievement.