The escape happened in Chapter 15 " A beating for Victor".
When the gang realized that Victor was following them, they quickly hid inside a souvenir shop to decide what to do. The children split up and left the shop one after the other to distract Victor's attention. Scipio disguised himself with Mosca's cap to find Victor in the crowd. Propser gave him some details about what Victor was wearing and Bo mentioned he wore a watch with a moon on it. Scipio found Victor and spoke to him briefly confirming his identity. Then the children left the souvenir shop together and started down a long and twisting alley. As Victor followed them, two large ladies stepped out of a cafe that he was passing and blocked his path. When he tried to squeeze between the ladies to keep following the gang, he found himself face to face with Hornet. She threw herself against him and screamed and shouted pretending to be attacked by Victor. The two large ladies started to hit him with their purses and he was finally arrested by the Carabiniere. During this commotion the children slipped away unnoticed back to their hideout.