Hare Sitting Up is a 1959 mystery thriller novel by the British writer Michael Innes.^[1] It is the sixteenth entry in his series featuring John Appleby, a detective with the Metropolitan Police. It is set against the backdrop of the Cold War.^[2] The title is taken from a quote from D.H. Lawrence's novel Women in Love. Reference is also made to the 1950 British film Seven Days to Noon.

Professor Howard Juniper, a top British research scientist working on developing a response to biological warfare has vanished and, even more alarmingly may have taken a vial of some deadly disease. Juniper would be a top target for kidnapping from a foreign power, or equally may be suffering from a nervous breakdown. In order to buy time, Appleby persuades his identical twin brother Miles, a schoolmaster, to take his place for a few days.

Appleby's investigations take him to the neglected country estate of a bird-obsessed earl and a top secret rocket base on an island off the northern coast of Scotland. Things are further complicated when the second brother also disappears.