Spanish police are frantically trying to identify possible ISIS collaborators who may have been plotting an attack on the Canary Islands after swooping on a Palestinian linked to the jihadis.
The suspected terrorist was found living under the cover of a busy holiday resort in Gran Canaria.
He had already tried once to get into Syria to fight with the rebel forces but was turned away at the Turkish border.
He returned to Spain, setting up home in the town of Vecindario, half way between the popular Playa del Inglés and Gran Canaria airport.
But unknown to him, police kept him under surveillance since 2014 and swooped at Madrid airport when he made a second attempt to join jihadists in Syria.
There is no suggestion that there was any plot for a local attack but officers are trying to identify any other collaborators who might have helped the Palestinian to achieve his aims.
The man tried to get to Syria in July and on this occasion, was attempting to head for Jordan as an alternative route.