Lionsgate has uploaded the official trailer for the horror film Cobweb [COBWB]. Lizzy Caplan [LCAPL] and Antony Starr star as the parents of an eight-year-old boy who hears a mysterious, constant tapping from inside his bedroom wall. They insist the sound is only in his imagination, but he believes that his parents may be hiding a terrifying secret. Cobweb opens in theaters on July 21st.