S4, E7: In 1926, Agatha Christie disappeared for 10 days. Was it amnesia, a nervous breakdown, or a giant alien wasp?

Starring Fenella Woolgar,  Felicity Kendal,  Tom Goodman-Hill 

S4, E7: In 1926, Agatha Christie disappeared for 10 days. Was it amnesia, a nervous breakdown, or a giant alien wasp?