tracker ... streaker

streaker ----- starker

starker ... takers

(I think I made too many changes when I posted “streaker”. I changed a letter and added another letter. Fortunately, Waal’s post seems to serve as a fix, anyway.)

takers ... market

market ----- marked

marked ... darken

darken ... errand

errand----errant

errant ... narrate

narrate ----- arrange