The Prologue is the optional first mission in The Godfather: The Game. It is also called the Prelude.
In 1936, life in New York City was fairly peaceful following the end of the Pacification of New York. One morning, Corleone crime family's soldato Johnny Trapani gives his weekly cut to Corleone caporegime Peter Clemenza in Little Italy and informs that he will go with his wife Serafina to The Continental in order to celebrate.
When he arrives to pick up Serafina at family bakery. Suddenly, a bomb exploded and Trapani rushed to the nearby alley, being informed by his wife that his young son Aldo had been playing there earlier. Johnny was set upon by four Barzini associates, who dragged him into the alley.
He managed to beat down with a lump of wood and he and other three Barzini enforcers dead, but it was in vain, as he was met by Don Emilio Barzini himself, who ordered Pietro Testa and Barzini Capo to gun Trapani down, Trapani was killed due to the hail of bullets, with his son arriving shortly later after his death.
A crowd gathered at the site and Don Vito Corleone consoled the young Aldo, telling him to save his anger and promising that he will take his revenge when he is old enough.
This event was witnessed by a devastated Aldo, who was comforted by Vito Corleone. Vito told him to save his anger, and that one day, when he was old enough, he could take his revenge.
The Barzinis took over Trapani's Bakery, but decided to sell it to the Stracci crime family in order to distance Don Emilio from the scandal of Johnny's death.
Don Vito Corleone - Your father pays his respects to Don Vito Corleone, who is leaving the nearby Genco Olive Oil Import Company after a meeting. You remember him comforting you after the subsequent atrocity.
Peter Clemenza - Peter Clemenza, Don Vito's most trusted capo, is on hand to relieve your father of his tribute: a cut of a payment from the business and rackets Johnny manages.
Johnny Trapani: Your Father - Johnny was an extremely loyal member of the Corleone Family. You remember little of your father's job, only that he enjoyed his life, and the love of your mother, Saraphina.
Saraphina Trapani: Your Mother - You were a handful as a kid, but your mother always kept you in check, and she loved your father dearly. Your father's death took a terrible toll on her.
Don Emilio Barzini - Head of the influential Barzini crime Family (and of the same untouchable status as Don Vito Corleone) your father's "operations" angered him so much, he ordered a hit.
The prologue doesn't have an in-game name, but the official Prima guide refers to it as "Father's Day".
The Alley / Welcome To The Family