The implications of having a double are rather disturbing. Sure, we've all been told we have a doppelganger, but what would it actually mean to have a duplicate of yourself out there in the world--in the same city no less? Denis Villeneuve's Enemy (based on The Double by José Saramago) explores just that. Mild-mannered history professor Adam Bell (Jake Gyllenhaal) goes through the motions of his life with relative gusto, lecturing here, fucking his girlfriend Mary (Mélanie Laurent) there. But it isn't until Adam watches an obscure, locally produced (bear in mind they're in Toronto) movie recommended by a fellow professor that he discovers one of the extras is an exact clone of himself--making him yearn for the boringness of life before.
The name of Adam's double is Anthony Saint Claire. Though we never find out what Saint Claire actually does for a living apart from playing two-bit parts in bad movies, it's clear that whatever his job is affords him better accommodations than Adam's teaching salary. Saint Claire's wife, Helen (Sarah Gadon), suspects something strange is going on when Adam calls the house and she immediately mistakes his voice for Anthony's. Amid the backdrop of all this is a mysterious gentleman's club (the private kind that requires a key) with a woman's heel poised to stomp on a disgustingly large spider. The spider imagery, indeed, is an important piece of symbolism throughout Enemy, representing, in one respect, the tangled web of unresolvability that Adam has gotten himself into.
Ironically, while Adam may have started out as the more interested party in striking up an acquaintanceship with his lookalike, it is Anthony who pursues their, for lack of a better word, relationship further. Intrigued by how they could possibly be connected, Anthony even goes so far as to question his mother (played by Isabella Rossellini--always a good thing) as to whether she had another son. She denies such an accusation vehemently and then offers him some blueberries.
To make matters worse for Adam, Anthony has taken a shine to Mary after following her to her workplace one day. He then makes the excuse that since he assumes Adam "fucked [Anthony's] wife," it's only fair that he should have a go at Adam's girlfriend. And because Mary is oblivious to the emotional upheaval Adam is going through with his double, Anthony threatens to reveal all to her if he doesn't comply. By the third act, it's quite clear that where there are two versions of one person, there is always one side that is evil and one side that is good.
By the climax (or flatline) of Enemy, Javier Gullón's adaptation has displayed such incredible amounts of rich complexity that it doesn't even matter if you can't quite process the meaning of a giant spider hovering over the city of Toronto--or even a giant spider hanging out in Anthony's room (it's all very Kafkaesque). Plus, what kind of cohesion or concrete answers can you really expect from a movie starring Jake "Donnie Darko" Gyllenhaal?