The Greeks achieved victory in the Trojan war by erecting a wooden horse, manning it with soldiers and bringing it up to the gates of Troy. The Trojans, despite all the warnings that they got, brought the wooden horse into the city. In the dead of night the Greek soldiers left the horse and opened the city gates to their army, which brought about the fall of Troy. Figuratively used in the text in reference to the three friends the expression ‘Trojan horse’ means that they were planning to undermine the rotten medical service from within.