Travelling to Malta in search of answers about his father’s past, Alex and his best friends Tom and Kyra uncover the beginnings of a deadly plot by the criminal cabal known as Scorpia, and the identity of its charismatic and ambitious new leader.

When the government of the United Kingdom receive a horrifying terrorist threat, signifying Scorpia’s return, Alan Blunt and the Department begin to hunt for their old enemy, while in Malta Alex follows the trail of the shady scientist working for them to his secret laboratory aboard a decommissioned ship.

Believing Alex has been captured, Tom and Kyra and Jack must scramble to find him. As Scorpia demonstrate the power of their new weapon, Invisible Sword, Alex is confronted by the leader, Julia Rothman, and some uncomfortable truths about his family.

Cut off from his friends and forced to train with one of his greatest foes, Alex endures a punishing induction to Scorpia at their secret base, and must face off against a gang of ruthless trainee assassins.

To prove his loyalty to Scorpia, Alex is sent on his first field mission by Julia, with Tom and Kyra following close behind, hoping to rescue him. Meanwhile the Department attempt to discover the secret of how Invisible Sword works.

As Alex returns home on a dark mission of revenge, his friends Jack, Tom and Kyra are forced to enlist the help of unlikely allies to save him before he crosses the line and commits to Scorpia forever.

Captured and questioned by the Department about his involvement with Scorpia, Alex must rely on his friends to remind him who he truly is. But are there secrets about his past the Department still haven’t told him?

As Scorpia orchestrate the final stages of their plan to threaten the lives of an entire British city, Alex must again go undercover with the enemy in a desperate bid to stop Julia Rothman before it’s too late.