Chun Hai and Monk Du transported into an alleyway by the inn, Chun Hai had intentionally brought them here so they could quietly access the situation and work out a plan before proceeding.
Prince Houyi was not expecting Chun Hai to be back for at least another three days or so. Moreover, knowing Prince Houyi he would be very skeptical of Chun Hai returning without him hearing any news of Prince Rui's death.
After a bit of thinking, they settled on the story that Chun Hai came across Monk Du as he was on his way to Jingli city. Since Prince Houyi had expressed interest in learning the transportation technique, Chun Hai decided to bring Monk Du over instead of continuing with the assassination plan.
That way Prince Houyi could learn the transportation technique himself from Monk Du and could go murder his brother or whoever he wanted himself, the Chun siblings could go free and it was a win-win for all parties involved.
