Режиссер Леопольдо Савона - далеко не самый известный из итальянских хоррормейкеров, но это нисколько не отражается на "Билете". Фильм снят на стыке готического ужастика и джиалло. От первого он унаследовал оккультную тематику и красивые локации: полуразваленные замки и роскошные интерьеры 19 века; от второго - мрачного убийцу в черных перчатках. И хотя загадки, свойственной джиалло в фильме практически нет, в нем безусловно присутсвует чувство стиля, присущего италяьнским триллрам. А в качестве десерта нам регулярно подают красивых рыжеволосых женщин, которые  нисколько не стесняются своей наготы.

Blood`s ceremonies, insane love and incestuous relationships are the dominant elements in this film. As for its artistic value, Byleth still manages to surprise, since it represents the first genre film convinced from a perfectly pure movie-buff-like point of view, besides the incestuous thematic had not been documented on this way in an Italian horror movie.

Having been away from the family estate and his beloved sister Barbara for a year, handsome young nobleman Lionello (Mark Damon) returns to a shock: Barbara (Claudia Gravy) has married the older Giordano (Aldo Bufi Landi) in his absence.

The issue is more than one of brotherly concern; in any case Giordano is a suitable husband in every respect, cultured, considerate and embodying all the virtues of his class. Rather, it is that Lionello, whose nerves have always been somewhat fragile in any case, has incestuous longings towards his sister.

It may be merely a coincidence, but Lionello's return also coincides with a series of murders, beginning with a prostitute, Dolores, in town and continuing with one of the family's own servants, the maid Gisella. In both cases the killer's modus operandi is the same, the victim having been killed by a precise strike to the neck from a distinctive three bladed weapon.

Coupled with a number of other signs – the sight of a white horse, a tremor – it leads the local priest to suspect that a demon, Byleth, may be abroad on the earth and in their midst.

Meanwhile, Barbara and Giordano have invited the beautiful Floriana (Silvana Pomilli) to come stay with them, in the hope that a romance with Lionello might blossom or, if not, that her presence will at least keep him from brooding on things...

Written and directed by the enigmatic Leopoldo Savona, Byleth – il demone dell'incesto  is one of the more ususual possession-themed films to come out of Italy in the 1970s on account of its historical rather than contemporary setting and the nature of its victim. Both these distinctions can presumably be put down not only to the film's pre-Exorcist  origins but also its somewhat more aspirational nature, whereby the sex side of the sex and horror material is often framed in the context of Lionello's sickness and voyeurism in a way that makes us aware of our own 'sinfulness'.

Another obvious point of comparison is Joe D'Amato's undeniably muddled but haunting Death Smiles on a Murderer, with which the film shares its incest theme and that general air of decadence and malaise.

Though perhaps inconsistently directed overall – a set-piece friendly duel turned competitive between Lionello and Giordano is full of dynamic camera movements and cutting, whereas expository scenes tend to remain bland and by the numbers – and lacking in a strong detective subplot or central character to engage the less committed viewer, Byleth works nicely when taken as a mood piece in which atmosphere is prioritised over shock and suspense.