The Sentinel: Legacy is about a legendary retired vigilante’s search for a successor to protect his collapsing city as his greatest enemy returns to reclaim the streets.

Elias Wainwright, now in his mid-60s, lives in quiet retreat after decades as The Sentinel, the masked vigilante who kept Ironvale in check. Age and injury have ended his time in the field, but the city he left behind is slipping.
When Elias learns that Lucien Voss—his most dangerous and intelligent adversary—is being released from prison, he realizes that Ironvale’s peace is coming to an end. Voss is not interested in chaos; he wants control.

Elias knows he can no longer protect his city, not alone. He needs to find and prepare a successor. He turns to Kat Court, a world-class fighter with a shared history both with Elias and, traumatically, with Voss. Kat understands Elias. She is a skilled ally and is Elias’s moral conscience.

Elias finds Conly Manning, a gifted young athlete whose instinct is to protect rather than dominate. Elias sees potential; Kat sees the danger of shaping another life around violence. Elias teaches Conly much more than how to fight as Conly learns discipline, responsibility, and what it actually means to protect the people you love. Conly, in return, earns the role through hard work rather than simply being a chosen one. When he eventually discovers that Elias was once the legendary Sentinel it pays off all the secrecy surrounding Elias's past.

Between them, Elias and Kat train Conly—not to replace Elias, but to become something more sustainable. But Conly must overcome his personal fears. He doesn’t drive, gets around by bicycle and has a fear of heights. Kat’s relationship with both Elias and Conly adds humor and warmth to the screenplay, specifically when they train.

Once trained, Conly has difficulty with the life of such a hero, the seclusion and having to leave his old life behind, which was to look after his sister and her daughter. As Voss becomes stronger and more threatening, Conly realizes not what he is, but what he can become.

It is not until Voss sets fire to Kat’s gym, for not paying protection money, destroying Kat’s home and business and the peace she lives in, that she decides that it’s time to get more actively involved. Ironvale needs its hero and she’s all in.
The story builds toward a final confrontation. Elias with his new team. Conly and Kat prevent an arms war, only to discover that Voss’s entire plan includes the death of Elias Wainwright leading to the final battle and the emergence of Ironvale’s new protector – continuing the legacy.

Each character has a legacy to drive them. Elias looks for a replacement just as he replaced a previous Sentinel. Conly is ready to pick up the mantel, not out of some hero complex but because it is what is necessary to keep his city and family safe. Kat suffers and gains strength from a violent history between Lucien and her mother. Lucien shows that evil can survive, it just needs the right seeds. The story is indeed in the title.

Most comparable films are about an individual looking to an aging mentor to become a hero. This would be stories like Creed or Logan. This story is different in that it looks at the aging hero who is looking to train a new hero. Comparables in this case would be stories that capture the mentor/apprentice dynamic the likes of Obi-won/Luke Skywalker or Gandalf/Bilbo Baggins and their journey together.