A new series starts tonight on BBC Two called Trigonometry, which is a new love story set in "crowded and expensive London".

The scene is set with accomplished chef Gemma and her paramedic boyfriend Kieran living together in West London above Gemma's café.

Kieran and Gemma are madly in love. But, love alone can't pay café suppliers, or London rent.

The pair are barely making ends meet, and their different shift patterns mean they’re like ships in the night. 

To ease some financial pressure, they've decided to take in a lodger.

Enter Ray - a former world-class synchronised swimmer, whose arrival with a Volvo full of baggage commences a modern-day love story that will change the trio's lives - and how they view relationships - forever. 

A polyamorous relationship ensues with each housemate learning about love and relationships in an entirely new way.

Trigonometry is on BBC Two at 11.00pm Sunday,