After a tumultuous school term, a family holiday with sunshine, sleep-ins and Portuguese tarts is just what Kensy and Max need. And Granny Cordelia is adamant: there are to be no investigations while on vacation. But when strange incidents start piling up, the twins are torn between their loyalty and their nose for adventure. As all leads point to the annual E-Prix championship, Kensy and Max find themselves drawn into the middle of a menacing plot. High-powered sports cars are not the only dangers on the streets of Sintra. Someone wants Wolf Motors and the Formula E car race to go up in smoke, and they won’t let anything – or anyone – get in their way.

Back at Alexandria, with their friend Curtis Pepper visiting, Kensy and Max are enjoying the school break. Especially when Granny Cordelia surprises them with a trip to New York! It's meant to be a family vacation, but the twins soon realise there's more to this holiday than meets the eye. The chase to capture Dash Chalmers is on and when there’s another dangerous criminal on the loose, the twins find themselves embroiled in a most unusual case. They’ll need all their spy sensibilities, along with Curtis and his trusty spy backpack, to bring down the culprit.

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.

What would you do if you woke up in a strange place? If your whole life changed in the blink of an eye and you had no idea what was going on? Twins Kensy and Max Grey's lives are turned upside down when they are whisked off to London, and discover their parents are missing. As the situation unfolds, so many things don't add up- their strange new school, the bizarre grannies on their street, the coded messages they keep finding and the feeling that, all around them, adults are keeping secrets . . . Things can never go back to the way they were, but the twins are determined to uncover the truth!

Kensy and Max are now agents-in-training at Pharos, a covert international spy network. A school trip to Rome provides a welcome distraction from worries about their missing parents. Amid the history and culture of Italy's capital, they discover a runaway boy and whisperings of Mafia involvement. It looks as if their harmless field trip might turn into their very first mission.