Mark enters a relationship with Sophie (Olivia Colman) and finds, quite rapidly, that... he doesn't really like her. This isn't anyone's fault, neither are presented as terrible human beings. They're just fundamentally incompatible and only end up steamrolling into marriage due to crippling mutual loneliness.
Merchant's first sitcom venture sans Gervais will be intriguing for a number of reasons; the most prevalent of which is that it will allow us to explore the notion that's long been mooted that Merchant is perhaps the more talented of the Gervais/Merchant pairing, with many citing Ricky's solo efforts as evidence to support this (Derek often being used as a stick to beat him with).