SoftUK are selling "Agatha Christie: And Then There Were None" for the Nintendo Wii for £19.49.
Use the code "Cheap Games" (without quotes) to get free delivery.
Next best price is £27.93 from The Hut.
You can get cashback via some sites (e.g. 2% Free Fivers, making it £19.10). You can also get 6% cashback through SoftUK's 'Collector' program
The storyline revolves around ten people, all strangers to each other, who are invited to a lavish estate on an isolated island. Through a recording, their mysterious host accuses each of his guests of murder and proceeds to exact justice by becoming judge, jury and executioner The tension mounts and dark secrets are revealed as one-by-one the number of guests systematically dwindles according to the ingenious plan of the unseen killer.