We pick up from Blue Bloods Season 11 Episode 2, with Frank saying that people will find out tonight who Joe is. Everyone gets quiet. Joe says he's still a Hill. Henry says they will respect Joe's wishes about how much distance he does or doesn't want to keep. Paula thinks this is her karma. Sean says it's helpful to be related to Frank. Eddie says she's glad she took the name. Joe thanks them for being so welcoming.

Erin and Anthony find a Christmas present on her desk. Anthony thinks he should be the one to open it just in case it's a bomb or anything nefarious. There's a photo of a criminal and a bunch of ledgers with his finances. Erin is suspicious and thinks an ex-mobster sent it to create trouble. The guy, Donnie, insists he didn't do it but Erin doesn't believe him.

A Ms. Diaz comes to see Danny. She says her grandfather was murdered recently.  She has video on her phone of the attack. It happened 5 days ago and he passed away yesterday. She reported it then but no one listened. She claims Jamie took the report and ignored it.

Danny talks to Jamie who says the woman told him God told her that her grandfather was pushed. Jamie feels bad that he didn't take the report when she came in the first time. Danny tells him not to beat himself up and they will find the guy together.

Frank is going over the decline in police recruitment. Sid jokes he hopes there are more Reagans out there they don't know about. He discovers everyone but him and Garett knew. Baker asks how Joe took it. Frank says okay but he doesn't know him well enough to know how he feels.

Garett thinks they should continue to celebrate Joe's heroism and add that he's a Reagan. Frank isn't sure that's a great idea and that Joe may not like it.

Sid comes to see Reagan. He's off the Diaz case. Jamie reported himself to his CO for not handling the case properly.

Erin and Anthony interview a mob boss who is supposedly immune to prosecution but say they can make charges stick if he doesn't cooperate. He gives them a name but Erin says they need more than that.

Danny comes to see Jamie. He says they need to solve the case on their own before Lieutenant G finds out.

Danny tells Baez is G catches them he'll take the heat. She doesn't like that idea. Danny and Baez go to talk to Ms. Diaz. Danny makes a connection with her over religion. He says she's protecting someone who killed her grandfather. She has a tattoo that says MG on her wrist. Baez tells her about her high school boyfriend and asks her not to protect her boyfriend. His name is Marcus and he runs with the Dead Twins. It was initiation night. They had to rob people. She insists Marcus had nothing to do with it.

Donnie comes to Erin and Anthony. He gave them the evidence. Erin says they don't need his help. He says if they want to bring down the whole family they need his help. He knows Johnny D'Angelo. Erin stares at him. He says he got what he came for and leaves. Anthony thinks they gave Donnie D'Angelo.

Danny interviews Marcus, who swears he had nothing to do with the murder.  Danny asks if he told anyone about the watch. Marcus said he loved Mr. Diaz and wouldn't hurt him ever. He witnessed it but saw nothing. Marcus asks for a lawyer.

Erin and Frank go to lunch. Erin asks if everything's okay. They talk about Joe. Frank doesn't like that they don't know Joe well enough to know how he feels about becoming a Reagan or the poster boy project. Frank says Joe loved the attention when he did his good deed. Now he has something to prove. Erin asks is Joe going ot look for other chances to be a hero? Frank says yes but that can be dangerous. 

D'Angelo is dead. Erin and Anthony argue about whether that's their fault or not.

Danny comes to see Jamie. Eddie gives them privacy. Jamie has heard nothing on the case. Danny updates him. Jamie says it's not his case and he can't be involved because he's under investigation. Danny gives him the file anyway and goes.

Everyone is playing poker and Danny starts up about Jamie getting in trouble. Frank says no talking shop at the table. Joe showes up with a black eye but doesn't want to talk about it. Finally he says he got in a fight in his command and they are offering him three days. Danny wants to know what happened. Some other cops said negative things about the Reagans. 

Everyone is talked out of going after the guys. Frank says all Reagans go through this and have to prove them. Henry says keep your head down and do your work. Joe says he always does. 

The mob boss denies responsibility. He wants to know how Hassett finds out. He says he'll help them his way. Erin and Anthony warn him not to take matters into his own hands.  He will need to cooperate or Erin will charge him with conspiracy. He tells them to check a dumpster on Newman Street.

Jamie tells Danny he's on the right track. They go to talk somewhere else. Jamie says he looked at Marcus' gamer tags and found some fake accounts the Dead Twins use. One of the newer guys is Andy Diaz.  G shows up and says he will give them 24 hours to finish the case. Danny asks Jamie to tag along.

Liz denies knowing where Andy is. She's not happy that Jamie is there. Then she insists Andy isn't involved. Jamie says they need to make sure Andy is safe. She says her mom makes them share location. She says that's weird. It says it's he's here when he's not. Danny and Jamie go to search for Andy. He's on the roof. He tells Jamie it was an accident. He didn't even want to join up. Andy threatens to jump. He thought it would be easier to mug his grandfather than a stranger and didn't think he'd fight back. He killed him.

Jamie says it was an accident. Andy can't live with that. Jamie says your family loves you. This is the last thing your grandfather would have wanted. You can still live a life he would be proud of. Andy lets Jamie take him off the roof and arrest him. Andy starts crying.

Anthony and Erin have found a gun in the dumpster. Erin says they have to put Rainer under protection, but not the way Anthony thinks.

Rainer sends his driver away and walkas up a path, where he finds Hassett with a gun. .The cops show up and surround Hassett. They arrest Hassett, who says he was just going to scare him. Erin is charging him with murder anyway.

Joe comes to see Frank. He has brought food for Sunday dinner. Frank says it's Saturday. Joe says he knows. Frank asks why the extra trip? Joe isn't sure he's gonna make it tomorrow. Frank asks him what about work on Monday? Joe says doesn't look good. He needs time to think things through. He has filed for leave. He was looking forward to meeting Nicky and Jack but they won't be here til tomorrow. Joe says he will try to make it. He doesn't want to miss them. He hurries away.

Everyone is happy about the food. Frank is looking out the window, waiting to see for Joe. Nicky and Jack show up and can't wait to meet Joe. Henry wonders where Joe is. Frank isn't sure he's going to make it. Everyone is disappointed. Frank doesn't know if Joe will ever come back. Nicky doesn't understand why Joe didn't stick around for dinner. She really wanted to meet him. The family talks about how everyone needs space from the family at some point. Frank is sure Joe will be in touch as it is almost Christmas.