Plot is unknown. Film is part of DC Extended Universe and will be the solo vehicle for Cyborg, following his appearances in Batman V Superman and Justice League.
Another DC character set to star in a DC Extended Universe standalone film is Cyborg, portrayed by Ray Fisher. Nothing much is heard about the development of the Cyborg project which was announced in 2014 but recent news confirms that it still on track for a 2020 release.
In the DC Extended Universe Cyborg has already appeared in Zack Snyder’s Batman v Superman: Dawn of Justice and he is also set to appear on Justice League: Part One and Justice League: Part Two.
Cyborg appeared first appeared in DC Comics Presents #26 as created by writer Marv Wolfman and artist George Perez released in October 1980. He was introduced as a member of the The New Teen Titans alongside Starfire, Raven and Beast Boy. They joined Original Teen Titan members and founders Robin, Wonder Girl and Kid Flash.
However in DC’s 2011 reboot he became a founding member of the Justice League. The DCEU will feature him alongside five of the seven original members of the JL namely Batman/Bruce Wayne (Ben Affleck), Aquaman/Arthur Curry (Jason Momoa), The Flash/Barry Allen (Ezra Miller), Superman/Clark Kent (Henry Cavill) and Wonder Woman/Diana Prince (Gal Gadot).
Two original members, Green Lantern and Martian Manhunter do not seem to be included in the film although the former seems to be hinted at the trailer shown at Comic-Con.
Before he became Cyborg, Victor Stone is the son of Cyberdyne Systems employee, Dr. Silas Stone (Joe Morton). The father and son were briefly shown in Batman v Superman: Dawn of Justice as was Aquaman and The Flash. They were shown in the laboratory where in Dr. Stone was seen trying to save his son.
Cyborg is considered to be a lesser known character compared to the other members of JL and Morton but Morton revealed that audience will get to know the dynamics between the father and the son more in the upcoming Justice League film to be released in November 2017.