letter bomb campaign
... that police used cryptic messages placed in a newspaper and disguised as Mensa puzzles to communicate with the perpetrator of a letter bomb campaign?
... that police used cryptic messages placed in a newspaper and disguised as <a href="./Mensa_International" id="mwBfs" rel="mw:WikiLink" title="Mensa International">Mensa</a> puzzles to communicate with the perpetrator of a <b id="mwBfw"><a href="./Tesco_bomb_campaign" id="mwBf0" rel="mw:WikiLink" title="Tesco bomb campaign">letter bomb campaign</a></b>?