Unable to pay for Monk's services as a private detective, middle-aged law student Julie Parlo offers him a trade--she'll help Monk become reinstated as a policeman with the SFPD if he'll help her find her missing grandmother. The only clue to the identity of the kidnappers is a roughly drawn lightning bolt on a note left at the grandmother's house, leading Stottlemeyer and Disher to suspect the former leader of an anti-Vietnam War group from the Seventies. But when the captain, anticipating Monk's reinstatement, invites Monk to help him with interrogation, Monk accidentally discovers that the suspect's tattoo doesn't match the symbol on the note--it has three humps instead of two.
Meanwhile, the kidnappers order Julie to provide turkey dinners to the homeless in exchange for the return of the grandmother. Julie complies and her grandmother is returned safely, leading Stottlemeyer to put the case "on the back burner." True to her promise, Julie informs Monk of a loophole that will allow him to get back on the force. All he has to do is to claim a disability and take a fifty-question multiple-choice test. Grateful for the information, Monk continues to investigate the case by asking the grandmother to relive her ride in the van. Her memories--the smell of a bakery, a four-minute stop during which no one got out, and the feel of rain drops as she was carried out of the van--lead Monk to the home of a pair of antique dealers, Harold and Carol Maloney. Sharona sets off the kidnappers' car alarm and Monk photographs them as they come out to investigate the noise. But why would a pair of antique dealers want to kidnap a seventy-six-year-old grandmother? Before he can investigate further, Monk has to take his test, which he's sure will be a piece of cake. And it would be, if it weren't for erasers that smudge and tear holes in the paper. A humiliated Monk locks himself in the captain's office--and discovers the clue he needs to wrap up the case.