The Impossible Gladiator (Time Keys Book 3), M G Leonard

Sim, Jeopardy and Nelson are enjoying an amazing holiday in Rome, until they they are swept up in the mysterious disappearance of world-famous illusionist Kinetic.

He vanished during a live broadcast from the Colosseum, but he never reappeared. When Kinetic’s sister finds a strange description in a history book of a gladiator who sounds uncannily like her brother, the friends are determined to help. They travel through secret time doors to the spectacular — and deadly — Colosseum in Ancient Rome, but can the brave trio survive long enough to find Kinetic and bring him home?