The Shield ends its seven-season, 86-episode run on FX tomorrow night with a series finale so cloaked in secrecy, it gives new meaning to the term “shield.”

After sending preview screeners of every episode, season after season, FX and creator Shawn Ryan decided that a DVD blackout was the only way to make sure that the finale didn’t wind up on YouTube or Chinese video before the fact.

After two invitation-only screenings in New York, critics in the hinterlands were invited to drop by Fox Sports Net offices, exchange code words and secret handshakes, and screen the final two episodes. Finally, at the 11th hour, a link and log-in were provided for online streaming of the penultimate episode, which aired this Tuesday, and tomorrow’s finale.

However, I still can’t tell you anything. Sorry. Not a thing.

A true Shield fan wouldn’t want to know anyway. Right?

A modern morality play set in a crime-ridden Los Angels police precinct, The Shield debuted March 12, 2002, and challenged audiences with characters painted in every shade of gray.

Like HBO’s The Sopranos, The Shield upended expectations of how TV characters should behave. On The Sopranos, mobsters were also family men with mundane suburban problems; on The Shield, the cop-heroes were hardly heroic. They made headway against crime by breaking every rule.

The difference: The Sopranos and The Wire aired on subscription channel HBO. The Shield brought drama of premium-channel quality to basic-cable subscribers.

Ryan “would be the first to tell you that The Shield owes a debt of gratitude to The Sopranos,” FX president John Landgraf says. But The Shield has probably been “the single most important series in the young history of ad-supported cable television.”

From its first season, The Shield has been a mainstay of Top 10 lists. Multiple Emmy and Golden Globe nominations include an Emmy for star Michael Chiklis in 2002 and a Golden Globe in 2003, when the series was also named best drama.

After spending five seasons as TV’s mild-mannered Commish, Chiklis reinvented himself as a buff bully for The Shield.

Fans of The Shield especially want to know what’s next for Ryan, an executive producer on The Unit.

“I’ve been more concerned about whether we’d be able to end it properly than I have been about being able to continue,” he told TV critics in July. The finale “feels very much like a graduation, but it feels like a graduation where you did well in school. And you’re going to the next thing.”