The forthcoming CBS procedural Boston Blue may be a spin-off from Blue Bloods, but it's still making a distinct departure from the beloved show that spawned it.

Mika Amonsen will play Sean Reagan in the 'Blue Bloods' spinoff, 'Boston Blue,' a role previously played by Andrew Terraciano.

Danny Reagan’s youngest son Sean will look a little different when he appears alongside his dad on CBS’ upcoming drama series Boston Blue. Mika Amonsen has been cast as a series regular opposite Donnie Wahlberg on the Blue Bloods offshoot,