Legend has it: anyone who sees the Demon Cat of Capitol Hill will be cursed with bad luck. 10-year-old Fina Mendoza just saw it. And the last thing her family needs right now is more bad luck.

Fina's mom just died. So she and her older sister Gabby just moved to Washington, D.C. to live fulltime with Papa, a congressman from California. Fina loves riding the Capitol subways, grabbing snacks in congressional offices, and especially spending more time with Papa – even though he's always on the phone.

But after Fina encounters a mysterious cat, a string of disasters follows. Jars of spaghetti sauce explode. Her beloved Abuelita breaks her leg. And Fina's only friend in Washington, a congressional dog named Senator Something, becomes the target.

The only way for Fina to save her family from future "cat"astrophe is to solve the mystery of the Demon Cat of Capitol Hill.