Try turning it round for a moment and start trying to make it happen. Smooth off the rough edges.
Communication. Not by a mobile phone, surely. It doesn't make sense it was by mobile phone, does it? Voice and text messages are out. Put it on vibrate and the only thing you know is ... someone, somewhere is calling.
Therefore communication is likely to be by other means. Here's an idea that does not appear anywhere so far in the files. It is pure speculation, a hypothetical to get secure simple communication, within Sadie's theory.
The perps went to one of the local Chinese bazaars and bought two very cheap and cheerful signalling devices. Commonly called LASERS.
One was red. which meant stop, hide, or scarper. One was green, which means it was clear to go.
A communication system that is safer than mobile phones, dirt cheap, and practicably undetectable.
I am not saying it happened this way. I have no evidence to support that it happened this way. But it is going to be tough on anyone who claims to be sure it did not.
Fair enough. so the lookout could see as far as the gate and no further. He sees Matt or Russell by the gate. Both tall men who would be moving quickly; it's cold and they want to be back at the restaurant. Round the corner are two people in the middle of the abduction. Perhaps they are in the middle of a manoeuvre passing a child through a window. Suddenly the one outside the window sees a flickering red light from the balcony. (Can the balcony be seen from there (?)). If she had been sedated with chloroform, for example, she would have been in danger of either coming round or being sick by now, by the way. They have no way of knowing if the approaching man is going to enter the apartment either. What do they do?
Producing a theory is the easy bit. Finding someone to carry out such a risky job is the hard bit, unless they were too stupid to imagine the possibilities. Of course there's always the possibility that they watched all week. Perhaps they were confident that the checking was so infrequent that they didn't need to worry about hurrying or being disturbed. That would mean that the T9 exaggerated the frequency of their checks, though, which was one of the things which made the PJ think there was very little opportunity for an abduction. If they did that they hindered the investigation.