S1, E24: Mrs. Brown (Pamela Britton) becomes snoopier than usual after taking a mail-order detective course. To practice her sleuthing skills, she immediately places Uncle Martin under secret surveillance. In so doing, the would-be gumshoe takes a picture of Martin's flight log, and mails it to her correspondence-school teacher J. Nathaniel Pierce (Cliff Norton)--and Martin must now retrieve the "evidence", lest he be revealed as a Martian (or at the very least, suspected of being a foreign spy!)