A Good Drama To Watch With A Parent (No romance)

Hello. I would like to watch a drama with my mom, one I haven't seen yet. She's okay with all genres except ones that involve a lot of romance. She prefers action, so I'm thinking maybe a historical drama? 

Any recommendations would be nice :)

Six Flying Dragons (2016) - historical about politics from Goryeo to Joseon. 
Jewel in the Palace (2003) - Not action, but has a bit of the palace politics in the kitchen. 
Cruel/Heartless City (2013) - Action and crime with gangsters and police
Signal (2013)- Crime and murder cases. Butterfly Effect also thrown in the mix.

Bitter Blood 

http://mydramalist.com/9136-bitter-blood

My Boss, My Hero

http://mydramalist.com/98-my-boss-my-hero-2006

Bloody Monday

http://mydramalist.com/14-bloody-monday

We're watching Signal now. Thank you everyone for the suggestions :)

Signal is a great choice! 
Otherwise there is Bitter blood. Maybe not the best ending, but it's really funny !
bloody Monday is like a typical serie with everything you want 
heartless city is a bit more mature and has that undercover+gritty feeling