BREAKING NEWS:  Amy Ryan, President of the Boston Public Library, resigns.

The setting was majestic, The Abby Room of the Boston Public Library with its 1895 murals depicting the quest for the Holy Grail. The message, however, was political hardball.

At a special meeting of the library trustees convened to address issues arising in the wake of the apparent loss of two prints worth an estimated $630,000, mayoral chief of staff Daniel Koh – in effect – accused trustee chairman Jeff Rudman of protecting library president Amy Ryan.

It was a highly unusual move, perhaps unprecedented.

In response, Rudman was clear that Ryan still had his full support.

After the meeting Ryan told the press that while this was hurtful, she had no plans to resign.

Koh made it clear that the patience of Mayor Marty Walsh was nearing its end.

The issue of the missing artwork, said Koh, was not being “taken as seriously as it should be.”

Koh also said that he and the mayor fear that even more may be missing from the storied special collections.

After the formal session, library chief Amy Ryan disclosed another report of missing valuable material -- this time pages from a music manuscript.

When it came time for comments from the public, two members of the Friends of the Public Library, a grass roots group, called upon Rudman and Ryan to resign.

On the face of it, that may not sound like much. But in the social ecology of the library, where there may be loads of private criticism but very little open dissent, it was telling.

The politics of all this are convoluted.

By state law, the library is an independent entity. The mayor appoints the trustees and the trustees name the library chief.

Rudman was recently reelected chairman of the board, and Ryan has Rudman’s support.

But in light of Koh’s statement, it seems only a matter of time before Ryan is gone.