Truly Madly Guilty focuses around a suburban barbecue, during which something bad happens that literally everyone there blames themselves for. We don’t find out exactly what happened, though, until the end of the novel.
The novel follows two time streams. The first is a couple of months after the barbecue, when everyone is trying to process reactions to the event. Erika attends a talk that Clementine is giving about the event precisely because she has gaps in her memory. But she is unable to listen, because the whole thing upsets her too much.
Back on the day of the event, Erika and her husband Oliver have invited Clementine and her husband Sam over because they want to ask them something important, a favor. Erika and Clementine have been supposed best friends since school, but Erika is unaware how Clementine resents her. Years ago, Clementine only befriended Erika to please her mother, who felt sorry for Erika.
Erika and Oliver’s expansive neighbor Vid interferes with their plans. When he hears Clementine and Sam and their two little daughters are coming over, he invites everyone to his place for a barbecue.
Erika’s confusion results from her being so nervous that she takes an entire pill of a sedative that her doctor has told her to try half or a quarter of. Then she uncharacteristically drinks, causing problems with Oliver, whose parents are alcoholics.
This novel untangles the events of that evening while it explores the relationships between the two women and between them and their husbands. I don’t think it was the best or most suspenseful Moriarty I’ve read, but her novels are always eminently readable.
whatmeread 
I have yet to read any of her books, but I would like to try one. Which do you like best?
So far, the one I’ve liked best was Big Little Lies.