The Three Chambers - Rosalie Bent - Bog

All boys wish there were secret rooms hidden underneath their house waiting to be explored. When Ben discovers such a room he launches himself and his two friends, Thomas and 'Lizard' into a fast-paced adventure filled with action, time-travel, near disaster and even a curious old alien. And in the middle of this incredible adventure, two of them find out more about themselves and their origins than they ever wished for.