The 'Maze Runner' writer is working on the script for Allegiant: Part 1 as production continues on next year's sequel 'Insurgent', reported Digital Spy.
The third novel in Veronica Roth's dystopian series is being split into two parts, with the films set for release on March 18, 2016 and March 24, 2017 respectively.
Stars Shailene Woodley, Theo James and Kate Winslet will reprise their roles in next year's sequel, alongside new cast members Naomi Watts and Octavia Spencer.
Meanwhile, Robert Schwentke has taken over from Neil Burger as director. Burger cited "practical issues" as the reason for his departure.