Firth returns to the small screen after a 25-year absence to play a man accused of murdering his wife, who he claims fell down a flight of stairs. SUBSCRIBE to GMA's YouTube page: SIGN UP to get the daily GMA Wake-Up Newsletter: VISIT GMA's homepage: FOLLOW GMA: TikTok: @gma Instagram: Facebook: Twitter: #GMA #ColinFirth #TheStaircase #OperationMincemeat #MammaMia