Secret Heirs of Billionaires Series by Kim Lawrence

He’s supposed to find her… …not seduce her! Greek tycoon Zach Gavros has one mission: to track down the long-lost granddaughter of the mentor who helped him rise from the streets of Athens to unrivalled success. But Zach quickly realises that introducing feisty Katina to Greek society could be more trouble—and temptation—than anticipated! Especially when their startling passion only confirms the power this untouched heiress has to undo him…