Four and Twenty Blackbirds (S01E04)

In a familiar London restaurant, Poirot observes a fellow patron straying from his typical order. Meanwhile, in Brighton, the elderly Anthony Gascoigne is on his deathbed, while his long-estranged twin, Henry, meets a sudden demise in a fall. Was it merely an unfortunate accident, or something more sinister? As Poirot delves deeper, he uncovers intriguing links between the events and concludes that the key to unraveling the mystery may be hidden within a seemingly innocuous blackberry pie.