The film plot implies that Altobello wants in on Michael investments as he tries to complete his family's move from crime-based profits to legitimate business. Altobello skillfully hides his nefarious intentions for the most part. However, Michael becomes suspicious of his motives after Joey Zasa, a Corleone Family rival, orchestrates an assassination attempt on Michael and other family heads assembled for a Commission meeting in Atlantic City. Altobello leaves the conference room before the attack. Michael escapes without injury, but many of the others in the room are killed. Michael then instructs his nephew Vincent Mancini-Corleone to go to Altobello and pledge his allegiance to him, without promising to betray Michael.
While in Sicily, Altobello enlists the services of an assassin, Mosca, who conspires to kill Michael at the Teatro Massimo opera house when his son Anthony is set to debut in Cavalleria Rusticana. Before the performance, Connie presents him with a box of cannoli as a birthday gift. It is implied that he suspects the cannoli is poisoned and asks Connie to have some, so Connie barely nibbles a piece, reassuring Altobello. The cannoli does turn out to be poisoned, however, and Altobello dies in his seat as Connie watches sadly through her opera glasses.