During a normal day in their backyard, Phineas, Ferb and Isabella are abducted by aliens, prompting Buford, Baljeet, and Candace to try and rescue them while Perry tries to help them from the shadows. Meanwhile, Doofenshmirtz is abducted as well as Vanessa. And they learn that the aliens want Phineas, Ferb, and Doofenshmirtz to build weapons for them and have kidnapped Isabella and Vanessa to use as collateral.
