The Break-in by Katherine Faulkner

 Alice and Jamie live in London and are the loving parents of little Martha. One day, Alice's friend Stella and her daughter are over for a visit. Jamie has run out for a bottle of milk when a crazed man breaks into their home waving a knife and looking for someone. Her mama bear instincts kick in and Alice hits him over the head with a metal stool, which turns out to be a fatal injury. Alice is consumed with finding out why the man chose their particular house. And figuring out why things keep going missing from her house, which is really bugging her but strangely not her husband. She also wonders why their long-time nanny decides to abruptly quit, knowing that Alice is about to start a new job. Alice becomes increasing frustrated that no one is taking her concerns seriously as she feels her life is spiraling out of control.

The story keeps bouncing around to different time periods so pay attention to the page headers. And watch out for an action-packed ending.