A Friendship That Became a Rivalry.
Why it is hard sci-fi
Two stage magicians compete by escalating their tricks. One uses a mechanical double. The other commissions Nikola Tesla to build a working teleporter that, in fact, is a duplicator. The film follows the engineering of both approaches, and the central reveal is that one of them is a magic trick and the other is technology.
Science inside it
Tesla coils, high-voltage discharge engineering, and the films one explicit physics conceit, a working machine that duplicates rather than transports its subject. The Tesla scenes are stylised but the laboratory model is the right shape for the period and David Bowies casting as Tesla anchors it.
Spoiler alert
Borden is two people. Twin brothers who have shared a single life since youth and trade off as needed. Anglers machine creates a duplicate every performance, and Anglers solution is to drown one copy each night while the other walks out the front. The film argues that both magicians used a hard mechanism. One was a logistic puzzle and the other was an engineered atrocity.