Inigo John Upcott is the husband of Katya Upcott, who is the assistant to Joshua Blay, one of the creators of The Ink Black Heart. Inigo and Katya have a son called Gus, who is a student of the Royal College of Music, and a young daughter named Flavia, who Inigo calls their “problem child.” The family of four live on Lisburne Road in Highgate and have a second home called Aquarelle Cottage in Whitstable, Kent.

Inigo is describes as having yellowish skin, untidy grey hair and thick lips. He wears half-moon glasses at the end of his nose. He “remarkably resembles” the German composer Max Reger.

Inigo is a sufferer of myalgic encephalomyelitis, or simply ME, and uses a wheelchair. The layout of their house on Lisburne Road is such that most of the rooms Inigo uses are on the same upper level to make it more convenient for him. Their son, Gus, occupies a bedroom on the ground floor and Flavia occupies a bedroom on the uppermost level. When Strike and Robin first meet him, Inigo refuses to shake hands, telling them that he has to be very careful about germs and viruses.

Inigo enters the room through electric doors while “The Show Must Go On” by Queen is playing from his bedroom-study behind him. Inigo is big into music, having once been an independent music publisher. Before getting ill, he also played guitar and keyboards in a rock band, and was a songwriter. He tells Strike and Robin that joining a rock band was a “despair” of his parents, and that he’s the son of a bishop. He is also a big fan of The Beatles.

When Dev Shah is watching the Upcotts’ house for Gus, Inigo emerges talking on his phone. Katya and Flavia are out. Dev calls Strike, who tells Dev to keep watching the house. Changing his mind, Strike calls Dev back and asks him to follow Inigo. Inigo ends up in a cafe, and Dev overhears him talking with someone he calls “darling child.”

We later find out that Inigo created a website called Tribulationem et Dolorum, where he writes about living with chronic illnesses and can chat with other sufferers. Inigo starts talking to Kea Niven on the site in 2013. Strike and Robin believe that she must be the “darling child” Dev heard him talking to over the phone. Strike and Robin believe it is no coincidence that Kea turned up on his website, and think she must have an ulterior motive to wheedle information about Josh and Edie out of Inigo, rather than creating a relationship with Inigo due to his personality and talents.

Wanting to talk to Inigo for a second time, Strike and Robin head to the Upcotts’ house in Lisburne Road. On arrival, however, they see Inigo and Gus pulling out. Strike and Robin decide to follow them in Strike’s BMW, driven by Robin. An hour later, they arrive at the Upcotts’ second home in Whitstable where they question him about his relationship with Kea Niven. Inigo tells them he thinks Anomie is Yasmin Weatherhead.