The mission 01011000 completes before this happens, but this is still part of the mission itself. As soon as Helle warns you about the intruders, you have a few options. If you are after a Pacifist and stealth route, immediately head back into Adam's bedroom. From there, you will easily be able to take the intruders one at a time. After minute or so of wandering around the apartment, they will make their way there . If you are taking a more aggressive approach, you can easily manage that from your present location.
In total, 2 mercenaries will break into Adam's apartment at the start. Deal with them as appropriate for the playthrough. If you are after stealth, wait for them to separate then take them down. Follow this with moving the bodies back into the bedroom from wherever you take them down. Loot the bodies to find another Pocket Secretary.
There are other mercenaries that have entered the area. They will be scattered through the apartment complex. Take your time and deal with them individually. They are on a much lower level of the complex.