Kill Box Checkmate. The World of Lizzy Ballard, #3.5

In a twisty tale of betrayal and vengeance, a cunning scientist orchestrates her escape from the isolated estate of a sociopathic tycoon. When Louise Mortensen's kidnapper, Theo Viklund, drops dead, she glimpses her chance for freedom-by becoming him.  Joining forces with Viklund's sinister head of security and her hapless lab assistant, Louise makes a chilling pact to conceal her captor's death. Once Louise assumes Viklund's identity, her path to freedom will be ensured ...
but first, she must access his biometrically protected computer accounts.  The key seems out of reach ... until Theo's brother arrives, searching for the truth behind Theo's disappearance. Will he provide Louise the clue she needs to unlock Theo's riches and his secrets?  Louise finds herself navigating a high-stakes web of deception, treachery, and murder. And the closer she gets to claiming absolute power, the deadlier her web becomes.  In this exhilarating thrill ride, a devious antiheroine with a murderous past must unravel a conspiracy of lies to claim a prize worth killing for.