The elder sister suspects her husband, Fu Chen, is impotent, so she asks her younger sister, Xiao Xue, to test him. Xiao Xue proactively entangles with Fu Chen, and their ambiguous push and pull crosses a line. Fu Chen's assertive performance shatters the "impotence" rumor. Upon witnessing this, the elder sister personally verifies, becoming deeply entangled and unable to extricate herself. She even tacitly allows Xiao Xue to seek out Fu Chen when she has needs. When Xiao Xue accidentally wets her clothes while showering, she has no choice but to ask Fu Chen for help, and this forbidden entanglement, which began as a test, spirals further out of control.
