Don't spook the Villain

Madam Lu's main room, the Duke's mansion 

 "lock her up in the detention cell at the back and put guards on her until we have decided on what to do with her. There is no need to question her, we might not get the right answer from her. Instead, she might claim it was someone else, like say me. That is going to be believable since I do have much to benefit from if something happens to the child. Brother-in-law can question her when he gets back and get the right answer. Meanwhile, let her be taken away".

Madam Lu followed her gaze and nodded. There was reason in what Su Liya said, she quickly understood that Su Liya intended to say something and she didn't want Tian Tian present. Madam Lu called in two of her guards, "take this treacherous maid to the detainment cell. I want around the clock guards on her"