Lan Wangji, recognizing the legitimate urgency in Magnus' voice, instantly stops what he is doing -- in this case, that entails setting aside the knob of ginger he is peeling, putting the knife in the sink so that no one is likely to inadvertently hurt themselves if he leaves it sitting out, and turning to Magnus. He doesn't see the need to say anything. He only nods and waits for Magnus to lead him wherever he needs to be.