Blind Lake by Robert Charles Wilson
Chris is a journalist who comes to a high-security national laboratory on the Canadian border to do a story. Suddenly the outside authorities lock down the perimeter of the several-acre compound (complete with a school, shops, restaurants, and a clinic like a military base). No one is allowed in or out, and the unexplained quarantine lasts for months with supplies being sent in by automated trucks. The “day workers” cut off from their homes and families in the outside world are especially distraught.
Chris needs a place to stay so he ends up with Marguerite, a recently divorced scientist with an awkward 11 year-old daughter Tessa recently diagnosed with Asperger’s Syndrome. Marguerite’s vengeful husband Ray is now the highest ranking manager in the compound since all the higher-ups were at a conference in the outside world when the quarantine happened; he becomes more and more unhinged and paranoid as the quarantine wears on.
Everybody thinks that the quarantine must have happened because of the work being done at the national laboratory: with the aid of a mysterious data-collecting device that has somehow evolved into a self-replicating Artificial Intelligence, the scientists have been secretly studying a representative of a mysterious insectoid civilization light years away. So are the insectoids the problem or is it the A.I.?
Nobody knows except maybe Tessa who seems to communicate with one or both through an entity she calls “Mirror Girl”. Chris and Marguerite find themselves increasingly drawn into conflict with Ray who wants to “pull the plug” on the project in which Marguerite has become completely emotionally invested. This is a solid, mature, complicated work filled with vivid minor characters.