From Deadline Hollywood:
One day after finding its Alex Rider, Sony Pictures Television has rounded out the full cast for its adaptation of the teen superspy drama. Game of Thrones star Brenock O’Connor and Stephen Dillane are starring alongside Doctor Who’s Ronkẹ Adékoluẹjo, Broadchurch’s Andrew Buchan and Line of Duty’s Vicky McClure.
O’Connor, who plays Olly in the HBO drama, stars as Alex Rider’s jovial best friend Tom. The Rider household consists of Alex’s housekeeper Jack Starbright, played by Adékoluẹjo, and Ian Rider, his detached uncle and reluctant guardian, played by Buchan. Unbeknownst to Alex, Ian has been relentlessly training him since childhood and preparing him for the threatening world of espionage.
Read the full casting announcement on Deadline: