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Episode guide

S8·E21 The Devil You Know

Core Aired May 4, 2018 45 min ★ 8.0/10 · 5 TMDB votes
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Synopsis

Frank locks horns with a data-tracking company when they refuse to unlock a terrorist's phone that may hold information regarding upcoming targets. Erin obtains information about an impending murder from a shady source.

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Frequently Asked Questions

When did Season 8 Episode 21 of Blue Bloods air?

Season 8, Episode 21 ('The Devil You Know') originally aired on May 4, 2018.

How long is Season 8 Episode 21 ('The Devil You Know')?

The runtime for this episode is approximately 45 minutes.

What happens in Blue Bloods Season 8 Episode 21?

Frank locks horns with a data-tracking company when they refuse to unlock a terrorist's phone that may hold information regarding upcoming targets. Erin obtains information about an impending murder from a shady source....

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