Lieutenant Polka-Dot, originally named Mary, is one of two Minifigures included with 6000 LEGOLAND Idea Book, along with her partner Bill.

In 1983, Mary was renamed to Lieutenant Polka-Dot, as one of the main characters in the Captain Indigo comic series for Bricks 'n Pieces magazine, with Bill/Captain Indigo as the star. Polka-Dot accompanied Indigo through various adventures, and while Indigo slightly changed in appearance throughout the series, Polka-Dot remained largely the same, aside from her skin being colored as flesh rather than yellow.

In the first story arc of the comic series, Polka-Dot was brought along with Indigo as a co-pilot while investigating a UFO. The two were sent back in time to the 'Kingdom of Avalon' by Emperor Bartok (Leader of the Zark planet) in order to retrieve the lost magical 'Zarconian jewel' of theirs, which was being controlled by a wizard and the Black Knight. While Indigo warned the Crusaders of the Black Falcons attack, Polka-Dot disguised herself as the blacksmith's assistant, and led the Crusader knights in defeating the Black Falcons.

In the second story arc, Indigo was arrested by robotic policemen and put in jail, but was freed by Polka-Dot. After a car chase with the androids, the two found the building from where the policemen were controlled, and Polka-Dot disabled the system while Indigo fought the creator of the robots, Tobor Rekam.

In the third and final story arc, Indigo and Polka-Dot were accidentally sent back in time by their robot dog T42. They then met Robin Hood, and set a trap to defeat the thieving Sheriff of Nottingham, who was then revealed to be Garth Raider, a space villain who was once shot down by Indigo.