The series focuses on Lucifer, 'who is bored and unhappy as the Lord of Hell and resigns his throne and abandons his kingdom for the beauty of Los Angeles'. While his meeting with a girl in his nightclub, a shootout at him and the girl leads him to be a LAPD consultant who in order tries to punish people for their crimes through police, law and justice.
Lucifer has done itself a lot of favors by selecting a strong lead performer, but Ellis can't carry the show all by himself. The show's writing is too tame to fully embrace all the implications of a main character who is literally the Devil.
Protests have been heard against turning Lucifer into a good guy, but in fact, he's mainly just a smug jerk with a creepy smile. And as his reluctant sidekick, German is as bland as her counterparts on a lot of better shows.