The Plumbers are trying to get a psychological profile of Daniel Ellsberg from the CIA. But the CIA resists; Plumber David Young eventually talked to Director Richard Helms directdly, making it clear that John Ehrlichman wants the agency to cooperate. Helms, however, continues to say that the White House has what there is, and that there's not much more they can do. Same from the FBI; on August 3, J. Edgar Hoover wrote a holding pattern memo to Plumber Egil Krogh. Nothing much is happening there.
And so they decide to take care of it themselves. Remember that memo that Plumber Howard Hunt had written to Chuck Colson with ideas of how to sink Ellsberg? Now, on August 3, Krogh and Young responded, telling Colson they would "look into the other suggestions Hunt made."
As Fred Emery says, they were all about to cross over the line from dirty tricks into felonies.
I'll also point out again that among other things, one way to think of all of this is as a classic example of presidents failing to get the bureaucracy (in this case the CIA and FBI) to do things that they want done.