The actor takes over from Bart Edwards in the show, which opens at the Arcola on 2 July
Jamie Muscato will join the cast of new musical The House of Mirrors and Hearts, which opens at the Arcola Theatre on 2 July.
Muscato will take over as Nathan from the previously announced Bart Edwards, who has had to withdraw from the production due to unforeseen circumstances.
The House of Mirrors and Hearts centres on a dysfunctional family haunted by their past. When Anna's husband is killed in a tragic accident at their home, her family's life is changed forever.
Jamie Muscato has theatre credits including Dogfight (Southwark Playhouse), The Light Princess (National Theatre), Rock of Ages, Love Story and Spring Awakening (West End).
The rest of the cast includes Gillian Kirkpatrick as Anna, Graham Bickley as David, Grace Rowe as Laura and Molly McGuire as Lily.
The production is presented by Aria Entertainment and Perfect Pitch and is supported by Grant For The Arts.
It runs at the Arcola Theatre from 2 July to 1 August.