In both, female leads come from Canada to Korea to uncover a mystery involving their sisters. Achiara is a much darker show than Secret Mother.

(I'm sorry if this sounds like a strange recommendation!!!)
Lee Duk Hwa plays similar (and adorable) characters in both of these dramas. Both characters have high political status, love children and aren't romantically loved. I personally pitied the characters. Even though he was so adorable he only suffered :(

These two dramas are pretty intense. The leads are desperate to save their loved ones. Both shows are filled with investigation and mystery.

Both dramas are pretty intense. A feeling of urgency is present in both as characters fight against time. Both shows are filled with mystery and investigation. Also, both leads have the same vibe.

Both shows deal with extreme situations where characters must find a way of surviving and saving people they care for...

In both shows the leads, while trying to save people they love, end up finding something they weren't expecting... Both are suspense thrillers with badass protagonists.

Suspense is very well done in both dramas. Although in different levels, there's lots of mind games and deceiving in both.

God's Gift is more of an action drama than Mistress is but in both dramas everyone seem suspicious and there's lots of mystery and suspense.

Both involve people trying to uncover secret organizations. Also, both are revenge dramas filled with action.

In both, people are framed for crimes they didn't commit, there are lots of injustice and also a lot of action. While watching Golden Cross I kept thinking of Two Weeks.

They are very different dramas but in both the leads have to scape from a very difficult situation.

Both are time travel suspense thrillers. In God's Gift, the female lead goes back in time to save her daughter from being murdered and in Tunnel the male lead travels to the future to catch a criminal he wouldn't have been able to catch in his time.