Disappearing ACT - Jacqueline Harvey - Bog

Kensy and Max are now agents-in-training at Pharos, a covert international spy network. Christmas break sees the twins back at Alexandria for training and a celebration like no other, but where are their parents and why can't they come home? Thankfully, a school trip to Rome provides a welcome distraction. Amid the history and culture of Italy's capital, they discover a runaway boy and whisperings of Mafia involvement. It looks like Kensy and Max's harmless excursion may just turn into their very first mission.