Blue Bloods season 9 episode 19, which airs on CBS in April, is once again going to center on Danny (played by Donnie Wahlberg).  Of all the people to team up with, the cop will need to work alongside his arch nemesis, Delgado (played by Lou Diamond Phillips). 

In the episode titled "Common Enemies," Danny arrives at Delgado's home under unfortunate circumstances. Someone has broken in and ended up killing his wife, and Danny knows exactly what Delgado is going through. 

According to the episode synopsis, Delgado will cooperate with Danny to find out who is responsible for the murder of his wife. Danny has reasons to be personally invested in this case as well, despite his loathing for Delgado, because whoever attacked the cartel soldier may be the ones behind the accidental death of Linda (played by Amy Carlson). 

It was Delgado who told Danny in a previous episode of Blue Bloods season 9 that his wife's death last season was not, in fact, an accident. The cartel he worked for might be behind the attack, and this knowledge has been hounding Danny's mind since the show's return. 

Danny even received a message from Linda through a medium in Blue Bloods season 9 episode 13, which aired last February. She told him that her death was not an accident; she was murdered. 

Now, Danny and Delgado are in the same boat as widowers in Blue Bloods season 9 episode 19. However, will they succeed in finding the real murders to finally get closure for what happened to their wives? Will there be a twist reveal in the end? 

Carlson's character was written off Blue Bloods after season 9 upon the actress' wishes. According to showrunner Kevin Wade, Carlson did not renew her contract with CBS.

"I was between a rock and a hard place because the simple fact of the matter was that [Carlson] decided not to renew her contract," Wade told TV Line. "And because that happened after we'd wrapped the previous season, we really had very little wiggle room, but we did the best we could with a tough situation." 

Meanwhile, Blue Bloods season 9 is on a two-week hiatus from CBS' programming schedule. It will return with a fresh episode on April 5 with Danny looking into a cold case. Is this tied to his pursuit to find out who orchestrated his wife's murder? Viewers should tune in to the CBS series to find out.