Franklin W. Dixon 
Dangerous Transmission 

ITD BE A CRIME TO LOSE THIS TOOTH While on holiday in London, Frank and Joe Hardy learn that a new inventiona voice transmitter that can be implanted in a toothhas been stolen. The prime suspect is a notorious spy who has recently been spotted in London, but shortly after the Molar Mike is stolen, the Hardys catch a trespasser in the lab where the transmitter originated. The suspect list is growing, and theres little time to spare. To catch this wily criminal, Frank and Joe need to hunt all over Londonfrom back alleys to the Tower of London. With new suspects popping up at every turn, and disaster threatening the teens, can they manage to sink their teeth into the crook before its too late?