The Judas Goat by Robert B. Parker

The Judas Goat - It’s been a year since Hugh Dixon’s family was killed in a terrorist bomb in London, England.  He hires Spenser to find the nine bombers and bring them to justice.  Dixon gives the nine Identikit pictures that were created from his description, $5000 advance, and a promise to pay $2500 per head to Spenser.  With nothing to go on, Spenser puts a personal ad asking for information about the bombing into a London paper.  Spenser then becomes a target for the group, Liberty.  Spenser and Hawk track the terrorists through Europe to the Olympic Games in Montreal.