Where can I watch “Moriarty the Patriot” Season 1 Episode 21 online?

This page provides episode info and a legal-only guide. It does not host streams or downloads. Check official platforms and licensed services for availability in your region (US first).

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Watching earlier episodes in season 1 helps you follow the plot and character arcs leading into this episode.

Watch Moriarty the Patriot Season 1 Episode 21 Online

“The Sign of Mary” — Watch "Moriarty the Patriot" Season 1 Episode 21 online in HD for free. Check streaming providers, cast, and episode details.

Jun 6, 2021 Season 1 Episode 21 24 min TV-14

7.7 ★ ★ ★ ★ ★

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Moriarty the Patriot Season 1

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Season 1 Episode 21 — Aired on Jun 6, 2021 • runs about 24 minutes.

Directed by Daiki Kato.

Written by Taku Kishimoto.

Notable cast/guest names in this episode include Soma Saito, Takuya Sato, Chiaki Kobayashi, Makoto Furukawa.

This page includes 4 official still(s) (when available) plus legal availability links.

Looking for “watch Moriarty the Patriot Season 1 Episode 21 online”? This is a legal-only guide with synopsis, stills, and navigation for this season.

Synopsis

John introduces Sherlock to Mary, his fiancée. A stunned Sherlock realizes that Mary has another concern. She produces six pearls, detailing their connection to her missing father. She asks Sherlock to look into the matter, but is holding something back.