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"Down the Rabbit Hole"

When serial killer Thomas Wilder (Louis Cancelmi) attaches a message to his latest victim that taunts Danny, their deadly game of cat and mouse becomes personal for Danny.

"Down the Rabbit Hole" (Episode 20, Season 6)

The Reagans gather in their dress blues.

"Down the Rabbit Hole" (Episode 20, Season 6 of Blue Bloods)

Erin Reagan rushes onto the scene.

"Down the Rabbit Hole" (Episode 20, Season 6 of Blue Bloods)

Detective Danny Reagan approaches a crime scene.

"Down the Rabbit Hole" (Episode 20, Season 6 of Blue Bloods)

Henry Reagan, Jamie Reagan, and Edit Jenko look on.

"Down the Rabbit Hole" (Episode 20, Season 6 of Blue Bloods)

Serial killer Thomas Wilder is back.

"Down the Rabbit Hole" (Episode 20, Season 6 of Blue Bloods)

Linda Reagan joins Detective Danny Reagan at a ceremony.

"Down the Rabbit Hole" (Episode 20, Season 6 of Blue Bloods)

Detective Danny Reagan approaches a troubling situation.

"Down the Rabbit Hole" (Episode 20, Season 6 of Blue Bloods)

Erin, Nicky, Jamie, and Henry Reagan sit quietly.

"Down the Rabbit Hole" (Episode 20, Season 6 of Blue Bloods)

Something sinister dawns on Detective Danny Reagan.

"Down the Rabbit Hole" (Episode 20, Season 6 of Blue Bloods)

First Look: Serial Killer Thomas Wilder Is Back

"Down the Rabbit Hole"

The Reagans gather in their dress blues.

Erin Reagan rushes onto the scene.

Detective Danny Reagan approaches a crime scene.

Henry Reagan, Jamie Reagan, and Edit Jenko look on.

Serial killer Thomas Wilder is back.

Linda Reagan joins Detective Danny Reagan at a ceremony.

Detective Danny Reagan approaches a troubling situation.

Erin, Nicky, Jamie, and Henry Reagan sit quietly.

Something sinister dawns on Detective Danny Reagan.