Note that if the color matches the current plot, you can decrease or increase the cost by 1. (I can't bother to check now if that could apply in the example, probably not.)
The example doesn't state the current plot so now way to know (but that hasn't come up in the rules yet). But the graphic showing the marker moving has it light shifting 3 spaces - which matches the card cost of 3. It is just a typo in the text.