Legends

Martin Odum's job is to become somebody else convincingly enough that dangerous people will trust him. Legends takes that undercover premise and begins asking how secure he is in the identity he returns to afterwards.

Sean Bean is the attraction. He can make an operative seem experienced without making him entirely in command of the situation, which gives the uncertainty somewhere to settle. The more the story stays with that uneasy relationship between a working cover and a private self, the more interesting it is.

The series changes direction as it develops, and its larger mystery is not always as compelling as the lead performance. I did not continue with it, so this is a qualified option for viewers specifically drawn to Bean or the premise rather than a broad recommendation.

The Americans is the stronger long-form exploration of living inside a cover story. Counterpart adds a science-fiction variation to identity and espionage. Legends approaches the territory through a more conventional thriller structure.