The Fowl Twins Get What They Deserve (The Fowl Twins #3) by Eoin Colfer

Irish Twins Myles and Beckett, Artemis Fowl's younger brothers, return in their third and most bizarre adventure yet, now in paperback.

*"Like its bestselling progenitors, a nonstop spinoff afroth with high-tech, spectacular magic, and silly business."--Kirkus (starred review)

For almost two years, Lord Teddy Bleedham-Drye, the Duke of Scilly, has been plotting revenge against the Fowl Twins, who humiliated him in Book One. Teddy plans to give them exactly what they deserve: permanent death.
He threatens Myles with his weaponized jet and Beckett and Specialist Lazuli succeed in disarming the aircraft and causing an accident that kills the duke. But does it really?

Ghosts, clones, and fairy magic come to play in this ultimate and ridiculous showdown between the twins and their worst enemy.