The party itself starts noticing that their robot seems to have a surprising number of hidden abilities that are quite powerful they were not aware of, and suspect that it is a hell of a lot more powerful than they have been led to believe. They also find people dying around them, that they vaguely remember seeing, in extremely violent ways as the syndicate clears its path. They get paranoid, especially as the murders all have at least one piece of evidence left to indicate they were spyign on the players. Their injuries are reasonably consistent with the firepower of this robot, to try and get them not to trust it and seperate them. When that doesn't work, they find a means to get the players and the robot seperated voluntarily, for which you'll have to find a way because you'll never be able to predict their reactions. The moment the seperation is arranged, the syndicate moves. The players are rendered helpless by whatever means is most expedient and preferably in a way that demonstrates massive resources. They are then immediately taken to the secure location where they are kept rom leaving and the figure responsible for the retrieval operation explains exactly what it is that happened, how he regrets having to involve them, and all that in the polite sort of tone that tells you they are going to kill you as soon as their work is done and nobody will ever find the body, but it's just business.
Then, sounds of combat. The figure says that this is probably their robot arriving to rescue them, knowingly charging into their trap because that is just the way they are. He explains their defenses in enormous detail, describing the resistance the robot is facing at each level, and every the robot has overcome one, expresses only mild surprise before explaining that he cannot possibly survive the next one.