Spoiler warning: Spoilers for the complete film or season named below.
Matthew is alive and is David’s biological son, not Hayden’s. I Will Find You connects the abduction to a mistaken identity at a fertility clinic and a falsified paternity result, then shows David surviving the attempt to bring his child home.
Why does Hayden believe Matthew is his child?
Cheryl visited the clinic using her sister Rachel’s name, although she was already pregnant. Hayden therefore connects the child to Rachel, his former partner. His mother Gertrude manipulates the paternity result, making him believe Matthew is his.
Those are separate layers of deception. The name on the visit does not establish who was pregnant, and the test Hayden trusts does not establish biological parenthood.
David begins the story imprisoned for his son’s supposed murder. The cast introduction emphasizes a man who has stopped imagining a future until a photograph makes the child’s survival possible. The clinic explanation finally accounts for why someone might have taken that child in particular.
Whose body was used to fake Matthew’s death?
Hayden substituted the body of another boy, murdered to support the deception, and manipulated the identification. Matthew had been removed rather than killed.
The frame-up also intersects with Nicky Fisher’s separate revenge against David’s family. Nicky’s interference with evidence should not be confused with knowledge of where Matthew was being raised; the official explanation separates those parts of the case.
The distinction prevents the ending from becoming a single conspiracy with one person responsible for every decision. David has been trapped by actions whose motives overlap without being identical.
Does David survive the rescue?
Agent Greer kills Hayden during the final pursuit. David is shot, but the later time jump establishes that he survives and his conviction is overturned. Matthew is reunited with the family.
Eight months later, the story attends Lenny’s funeral and the lives that have continued around the case. David and Rachel share a quiet moment rather than a complete plan for the future.
Reuniting father and son answers the central search. It cannot restore the years lost in prison or erase what Matthew has been told while growing up elsewhere.
The final promise is about remaining available to the child after the danger ends. David’s task changes from finding Matthew’s location to helping him live with the truth of how he came to be there.
Sources: official ending breakdown; official interview or additional context.