The plot of Sybil at Sixteen is straightforward, although several subplots are interwoven on the way to its resolution. The major plot involves Sybil's efforts to help her father gain a financial stake that will help to get him started again on his business ventures.

Mysteries involving Evvie and Sam and even Nick, himself, are solved during the course of events. Certain longstanding misunderstandings among the sisters are corrected. The case of Sam's mother, Sybil's stealthy activities, and Nick's final disposition generates suspense, which is built through descriptions of situations and of characters' inner conflicts as well as through the technique of foreshadowing. Although a narrative, Sybil at Sixteen is developed mainly through dialogue. Flashbacks are used to establish background necessary for understanding current events and to illuminate traits of the characters. A sense of reality is heightened in the story by use of names of...