From the Super Mario Wiki
Koopa Capers is the fourth book in the Nintendo Adventure Books series, first published in August 1991. It is also notable in that Mario does not make an appearance in it, with Luigi mentioning he is busy "fixing a drip" at Niagara Falls.
The Story from the Back Cover:
Koopa Kid Kidnapped! Luigi to the Rescue?
Wendy O. Koopa has disappeared and an embarrassed King Bowser asks the Super Mario Bros. to find her. Experienced princess-rescuer Luigi reluctantly agrees. But all is not as it seems. Can Luigi trust Bowser and his creepy creatures-or does the treacherous turtle have a secret scheme up his shell?
As in all Nintendo Adventure Books, you control the action. Only you can make the choices that allow Luigi to beat Boo Diddly, Hot Foot, and the rest of the Koopa creatures. Help him crack codes, solve puzzles, conquer mazes, and subdue enemies. You and Luigi must outwit the Koopas at their own games-or go down in final defeat!
- 610 or more pts. — Rompin', Stompin', Wrenchmaster Supreme
- 510-600 pts. — Power Plunger
- 410-500 pts. — Fluid Mechanic
- 210-400 pts. — Plumber With Promise
- 200 or less pts. — Drained Brain
- ^ SMBHQ (Retrieved June 23, 2011)