String and Dom rescue Dom's niece from her abusive boyfriend and return her to the U.S. Unfortunately, the boyfriend hasn't given up on her yet and sends his goons in search of her. Caitlin O'Shaughnessy re-enters the picture, asking Dom for a job at his hangar. Meanwhile, while trying to assimilate to life in the U.S., Holly begins hanging out on a movie set with String and Dom. 

Dom and String return to Dom's birthplace when Dom learns that his daughter has died of a drug overdose. After attending the funeral, they return to California where Dom is arrested on suspicion of murdering his ex-wife. String returns to the island to investigate the murder and learns that unsavory elements have begun taking over the seaside community where a casino is being developed. String finds himself pondering a burning question...does the casino's developer have something to do with the deaths of Dom's wife as well as his daughter?