It's been six months since Fintan McHewell disappeared. Fintan's son Mark and wife Bree are just learning to live without him when Mark discovers a clue to Fintan's absence in, of all places, a peculiar story in a sci-fi comic. Following the clues in the comic, Mark and his friends Niamh and Ferdia uncover a cryptic wooden cube and a series of mysteries that suggest Fintan was leading a double life. A website run by the inscrutable Del Forgill leads them further into intrigue and as the deaths accumulate, so do the questions: What are the Tetroi? Why are mythological wooden flying machines stealing the GPS satellites? And what does the whole affair have to do with Simon Magus and the old disused lighthouse on Wicklow Head? Can a fourteen-year-old boy really expose a twelve thousand-year-old conspiracy and in doing so save his father ... and this tír?