Mammoth Books presents Substitutions

Taken from The Mammoth Book of Best New Horror 22, edited by Stephen Jones.

As Smith recalls: "This story came about in the simplest way, the way I always enjoy most - something happening in real life that makes you think ''What if?'' "Our household gets a lot of its food via an online delivery service, and one day when I was unpacking what had just been dropped at our house I gradually realised th...