[4] After the events in Winter Tide, siblings Aphra and Caleb Marsh decide to return to their people's fictional hometown of Innsmouth in New England, and rebuild it before property developers move in.

A review of Deep Roots in Publishers Weekly called the book an "absorbing continuation" of Emrys' Innsmouth Legacy series and its "treatment of cultural identities in conflict".

[5] The review said readers will appreciate her "subtle references to Lovecraft’s stories and her dexterous use of his tales’ set pieces for her own imaginative goals.

[1] She said it is a "well-crafted" book, and "continues to take H. P. Lovecraft's Cthulhu mythos in a new direction, echoing the themes of immigrants and governmental reaction.

"[6] A review on the Los Angeles Public Library website stated that Deep Roots and its prequel, Winter Tide are not just "horror novels", but "explorations of identity, culture, family, both by blood and those we create ourselves".