'Blue Bloods' Season 8 Episode 4 Air Date, Synopsis, Spoilers: The Reagans Investigate

It is business as usual in "Blue Bloods" Season 8 Episode 4. On Friday, the Reagan family play detective as Danny (Donnie Wahlberg) investigates the death of a witness and Frank (Tom Selleck) questions why Garrett (Gregory Jbara) was ambushed by the SWAT in front of his own house.

Titled "Out of the Blue," the episode will also see Erin (Bridget Moynahan) once again at odds with Anthony (Steven R. Schirripa). According to the synopsis published by Spoiler TV, the Assistant District Attorney is not one to back down so, in a recent case, she brings in an informant against the DA Investigator's wishes.

"Danny and Baez work the case of a detective who was gunned down prior to testifying against a career criminal," the synopsis read. "Also, Frank personally investigates when Garrett is attacked by a SWAT team outside his home, and Erin brings in a confidential informant against Anthony's wishes."

However, perhaps, the more exciting detail from the synopsis is about Frank who gets to go back into the field and investigate. As commissioner, he does not exactly take matters into his own hands as often and this episode can let the character remind the viewers that he is a skilled member of the police force. Frank also personally attending to the issue also means that something big has happened and something big might be coming. CBS has released a new promo for "Out of the Blue" which provides a little more information about the police commissioner and Reagan patriarch's mission this week.

Unfortunately, the synopsis for "Blue Bloods" Season 8 Episode 4 does not offer anything about what Jamie (Will Estes) and Eddie (Vanessa Janko) are up to next. They will still appear in the episode, but likely will take a back seat. Fans might have to wait a little longer to see their relationship take a major step forward.

"Blue Bloods" Season 8 Episode 4 ("Out of the Blue") airs on Oct. 20, Friday, on CBS. Watch the teaser below.