Sammy is the eldest son of the Fabelman family, which makes up of his mother Mitzi (Michelle Williams), father Burt (Paul Dano), and younger sisters Reggie (Julia Butters), Natalie (Keeley Karsten) and Lisa (Sophia Kopera).

Throughout the film, Sammy and his family move to different locations as a result of Burt receiving new jobs as a computer engineer, taking them from their hometown of Haddon Township, New Jersey to Phoenix, Arizona and finally, to Saratoga, California.

During his time in Arizona, Sammy, at age 16, becomes influenced by John Ford's The Man Who Shot Liberty Valance (1962) while watching it with his boy scout troop, who then help him make an 8mm short film inspired by it called Gunsmog, which earns him a merit badge for photography.

However, he discovers while editing footage he shot of a family camping trip that Mitzi has been having an affair with Burt's loyal friend and co-worker Bennie Loewy (Seth Rogen), who has often been seen as a surrogate uncle to Sammy and his sisters.

It is there when he starts attending Grand View High School and becomes the target of two jocks, Logan Hall (Sam Rechner) and Chad Thomas (Oakes Fegley), who levy antisemitic abuse towards him.

He later ends up dating the devoutly Christian Monica Sherwood (Chloe East), who asks him to film the school's Senior Ditch Day, an offer which he eventually accepts when she mentions that her father will lend him his 16mm Arriflex camera.

"[8] Gabriel LaBelle, who was picked from over 2,000 contenders to play the role, described that most of the events and situations Sammy faces in the film happened to Spielberg in real life, particularly the antisemitic bullying and his encounter with John Ford.

He could convey the pathos that was needed and also the humor," while Spielberg added, "I wasn't looking for what I see in the mirror, I was looking for a young actor who could carry a lot of story by being curious and honest and engaging and unpredictable.

[18] To look the part, LaBelle had his own hair cut and straightened, and attempted to copy Spielberg's own walk, hand movements and how he smiled to make the character look more like his inspiration while keeping him fresh and new.

[22] While the film hews closely to the events of Spielberg's life, some elements were created exclusively to add to the fictionalization of the story, notably the creation of Monica Sherwood to be Sammy's girlfriend.

Spielberg, like Sammy, did uncover his mother's affair with Bernie Adler (the inspiration behind Bennie Loewy) at age 16 and did keep it a secret from his family before Leah and Arnold divorced.

[26][27][28] Ed Potton of The Times noted that the "hallway scene" between Sammy and Logan was different from how the final encounter went down in real life, with Spielberg saying that the bully "came over a changed person.

Ryan McQuade of Awards Watch called LaBelle's performance the stand-out among the cast and praised the character of Sammy as "someone we can trust and connect with as we are seeing his story unfold.

"[33] Brian Truitt of USA Today said that LaBelle "pulls on your heartstrings as his character's filmmaking, this endeavor he adores, becomes the lens into a secret that creates a rift among his loved ones," positively relating to how various scenes make viewers watching the film become Sammy's eye for the camera.

"[35][36] The scene itself would also go viral on social media during the first week of the film's VOD release in December 2022, with users praising LaBelle's line delivery and resulting in the character of Sammy becoming popular through fancams uploaded to Twitter and TikTok.