River Cartwright

David Cartwright is River Cartwright's grandfather, referenced when Jackson Lamb threatens to reassign Roderick Ho to his office.

River and Kelly have a sexual relationship while River is undercover in the village of Upshott. Kelly is a bartender at the local pub 'The Dropped Stitches' and River is staying in the village under the alias Jonathan Walker.

Catherine is concerned about River's safety during his undercover assignment and hopes for his safe return. She works at Slough House with River.

River reports to Jackson Lamb as part of his undercover assignment in Upshott. Lamb directs River's investigation and provides operational guidance.

River Cartwright and Louisa Guy are colleagues at Slough House

Griff helps River after the confrontation with soldiers and provides him with a phone to call Catherine

River reflects on his former friendship with Spider Webb, now injured and in hospital

River inquires about Min Harper's death and questions whether it was truly an accident, showing concern for his deceased colleague.

River seeks Ho's technical expertise but Ho is generally dismissive of River

River is displeased that Shirley was assigned to investigate Dicky Bow instead of him

Amos Crane was a legendary operative at the Park before River's time

Meg is a local resident and mother of Damien Butterfield; she and River have friendly conversations in the pub about his supposed writing project.

Ray is a retired pilot and gray eminence of the flying club whom River is trying to meet but has been unable to locate.

Katinsky attacks River with an electroshock weapon and attempts to detonate bombs in the village