In the final Perry Mason novel, The Case of the Postponed Murder, Morrow provided no notes as to the provenance of the novel; however, a few key phrases make the reader suspect the manuscript was written some 10-30 years prior to its publication. Most suggestions point to a date of somewhere during the Perry Mason television show, but there are no notes in the archives to confirm this.
Sylvia Farr comes to Mason’s office, looking for her sister, Mae. Mae had been living in the city and writing home on a regular basis until recently. Sylvia wants to find the sister and see if she is alive and well. Mason points Farr to Paul Drake’s office.
In the meantime, Mason learns that Farr has been accused of forging a check by a rebuffed admirer, Penn Wentworth. Farr goes to Wentworth’s boat, they struggle for the gun and a bullet kills Wentworth. However, when Farr brings Mason back to the marina, the boat is out to sea. A somewhat impossible crime occurs when Mason tries to figure out how a boat with only the victim’s body on it could have launched itself.