Callie and her pet Bo, a mischievous mynah bird, have a secret. Whenever she puts in and switches on her hearing aids, she can hear Bo talk to her. It's amazing . . . though it can lead to trouble for them both! When Bo sneaks into Callie's bag on her school trip to the Tower of London, she and her best friend Grace must keep his presence hidden. But when some gold coins and jewels are stolen, it turns out that having a spy in the sky can come in useful!
