A Dangerous Time for Love by Louise Allen

Loving an earl is difficult enough when you are separated by over two hundred years. Add murder, jewel theft and divided loyalties and it becomes even harder – and more lethal.
Cassandra Lawrence is an independent modern woman with a big secret – her lover Lucian, the Earl of Radcliffe, just happens to have been born in 1779. Cassie might be getting used to finding herself back in 1807, even when Luc is involved in mysteries, murder and general mayhem, but the closer they become, the harder it is to leave him.
When they find themselves embroiled in a death and the theft of priceless jewels at his Suffolk home, Luc and Cassie have more than a killer to unmask – somehow they have to find a way to be together. And that might be as dangerous as anything they have yet faced.