Page Eight gives every sign of being a momentous television event. It is a debut outing for “Masterpiece Contemporary” on PBS. Some of the color photography, by Martin Ruhe, is exquisite but sinister—there’s a bruised sky against college masonry in Cambridge that escapes the usual proviso that television cannot be “beautiful” without seeming picturesque. The subject matter turns on such large issues as security, intelligence, Intelligence, honor, and love. The cast is so daunting it makes you keep an open mind about which characters are not to be trusted.