Start with these two words
INSANE RETROSPECT
and see if you can get them to exchange places by transferring one letter at a time. With each transfer, you may also rearrange (anagram) each word in any way you choose. However, each side must always remain a valid English word.
You are finished when you have reached
RETROSPECT INSANE
All the intermediate words should be fairly common, so you shouldn't have to reach for your dictionary. There is one word along the way which might seem a little unfamiliar to some, so I will give it to everyone as a guidepost: INTERCASTE.
Here is an unrelated example just to illustrate the movement:
MAGISTRATE DENSER
| . |
| . |
| I |
| . |
v . v
STRATAGEM DENIERS
| . |
| . |
| T |
| . |
v . v
MEGASTAR RESIDENT
| . |
| . |
| N |
| . |
v . v
MAGNETARS DIETERS
| . |
| . |
| A |
| . |
v . v
GARMENTS STEADIER
| . |
| . |
| M |
| . |
v . v
STRANGE DIAMETERS
| . |
| . |
| D |
| . |
v . v
GRANDEST STEAMIER
| . |
| . |
| I |
| . |
v . v
GRADIENTS STEAMER
| . |
| . |
| E |
| . |
v . v
DENIGRATES MASTER
Notice that at each step, you may transfer in either direction. You are not obligated to alternate between right to left and left to right.
Afterword:
Here is another solution using more familiar words:
INSANE RETROSPECT
CANINES PROTESTER
CRANNIES TREETOPS
CANNERIES PROTEST
NECTARINES POSTER
ENTRANCES RIPOSTE
REENACTS PROTEINS
EASTERN INSPECTOR
ASTERN RECEPTIONS
SENATOR PRESCIENT
REASON INTERCEPTS
PERSONA INTERSECT
PERSON INTERCASTE
OPENERS INTERACTS
PIONEERS TRANSECT
INTERPOSE TRANCES
PROTEINS REENACTS
RIPOSTE ENTRANCES
POSTER NECTARINES
PROTEST CANNERIES
TREETOPS CRANNIES
PROTESTER CANINES
RETROSPECT INSANE