Carmen Sandiego Word Detective is a game in the Carmen Sandiego franchise which was released in 1997. This game is intended to teach language arts for kids age 8-14. LearningVillage describes Word Detective as a "spy adventure". The title is very similar in format to Carmen Sandiego Math Detective, which was released a year later.
In the game Carmen Sandiego has invented a machine called the Babble-On Machine, and the user, playing the role of Agent 13, has to thwart her plans and free all the other agents which have been captured by Carmen.
The game comes with many bonus features, including "3 levels of difficulty, an electronic dictionary, 10,000 spelling words, customizable spelling lists, 50 spelling rules and an on-screen progress reports."
The intro starts off with Agent 12 (Ann Tickwitee), who has found Carmen's hideout. Under the orders of Chase Devineaux (The Chief-type character), she creeps inside, only to find herself trapped and start to babble. Carmen enters and explains that she has invented a "Babble On" machine that turns speech into gibberish.
When the player begins, they are Agent 13, who has just been called into the case. The player must "free all twelve agents in order to stop her grand plan to achieve world illiteracy". They do this by going to enemy hideouts and solving language problems in order to get passwords which allow then to retrieve keys which they use on the machine to free agents.
Source: Wikipedia, "Carmen Sandiego Word Detective", available under the CC-BY-SA License.