Double Trouble Squared: A Starbuck Twins Mystery, Book One

[shared copy] The Starbuck family is anything but ordinary. There are two sets of Starbuck twins: preteens Liberty and July, and their little sisters Charly and Molly. But even more extraordinary is the fact that all four children have the ability to teleflash—they can talk to each other without saying a word! It's a power that comes in handy whenever these adventurous kids are on the trail of a villian. 
 
When twins Liberty and July accompany their father on a business trip to London, a mysterious voice starts speaking through their teleflashing channels. Who is trying to contact them, and why? Using the detective skills of their hero, Sherlock Holmes, the twins set out to solve a puzzle that takes them on an exciting journey through the streets of London.