Arsenic for Tea is a children's mystery novel by American-English author Robin Stevens, published by Puffin Books.

The story is written in the style of a casebook, as the Detective Society try to solve the murder of a guest at a birthday party.

Daisy, while playing a game of hide and seek, then tells Hazel that they are going downstairs to spy on Mr. Curtis, as she thinks he is highly suspicious.

Later that day, whilst playing Sardines, Stephen finds Hazel and admits he is poor, and together they accidentally overhear Mr. Curtis say to bring certain things, including jewels and paintings, to Lady Hastings.

Daisy and Hazel, using the spare key, as Uncle Felix has taken custody of the main dining room key, enter the dining room early in the morning to recover the cup full of Arsenic, entering easily when they see the door unlocked, even though they were sure Uncle Felix locked the door.

Uncle Felix then says it was dysentery, which was why he didn't think it was food poisoning, and Lady Hastings then suggests that it was murder.

However, Lady Hastings is unable to call the police due to the roads being flooded and the connection not working.

Heading downstairs, they see Uncle Felix, Aunt Saskia, and Bertie try to stop Lady Hastings from calling the police.

In its review, The Daily Mail praises Arsenic for Tea as a sequel that “stands alone and is a delight”, and lauds Robin Stevens for how her “Agatha Christie-like clues are unravelled with sustained tension”.