Watch Site 13 (2023) HD Full Movie Free on SolarMovie. Watch Site 13 (2023) online free. SITE 13 is a Cosmic Horror film. When Dr. Nathan Marsh awakens from a catatonic state in a mental in...SITE 13 is a Cosmic Horror film. When Dr. Nathan Marsh awakens from a catatonic state in a mental institution, he must relive his last expedition by watching tapes from the site visit, only to discover he's unleashed an unstoppable horror.