Danny Reagan's (Donnie Wahlberg) will get too personal in his next case in the upcoming episode of "Blue Bloods" season 6.

In the episode, titled "Down The Rabbit Hole," Danny's crusade against serial killer Thomas Wilder (Louis Cancelmi) intensifies as the two get into a bloody game of cat and mouse when the NYPD discovers a new victim. But this time, Wilder made sure that Danny gets his message loud and clear.

Danny first encountered the deadly serial killer during the second episode of season 6, when he and his colleagues uncovered a number of dead women in a private area. Wilder began to at taunt him after Danny called him a coward on live TV.

Wilder started killing women again in episode 8, but he narrowly escaped death when TARU decided to blow up the boat where he was hiding. However, it seems like he will not stop until one of them wins their deadly chase.

According to the synopsis for the upcoming episode, "When serial killer Thomas Wilder attaches a message to his latest victim that taunts Danny, their deadly game of cat and mouse becomes personal for Danny."

But the fight between the two will also involve Danny's family. Based on the promo clip from the upcoming episode, Wilder manages to get hold of Danny's niece Nicky (Sami Gayle). This means that the entire Reagan family will do everything to rescue Erin's (Bridget Moynahan) daughter. "I just want my granddaughter back," Danny's father Frank Reagan (Tom Selleck) says in the trailer.

The trailer also reveals that this will be the final showdown between Danny and the serial killer. Will Danny manage to capture him this time?

"Blue Bloods" season 6 episode 20 airs Friday, April 15, on CBS.