The Flynn-Fletcher's neighbors have relatives visiting who bear an uncanny resemblance to Candace, Phineas, and Ferb. In fact, older sister Mandy has two younger brothers, Thaddeus and Thor, who drive her crazy with their ambitious projects. Although Candace and Mandy initially bond, they soon compete, urging their brothers to build the best backyard fort. Meanwhile, Perry finds himself in the middle of Dr. Doofenshmirtz's family reunion where Dr. Doofenshmirtz tries to win the annual kickball tournament with the Kick-inator 5000. / Phineas and Ferb set out to build a bigger plane than Howard Hughes' wooden Spruce Goose, so they build it out of papier-mâché, to do a similar theme to the Spruce Goose, complete with in-flight service and entertainment. Dr. Doofenshmirtz is doing his part to be green by using recycled materials to build an "Evaporator-inator" to dry up all the pools in the Tri-State area. Meanwhile, Candace and Stacy attend Jeremy's pool party only to discover an adventu